Questo lavoro è stato sostenuto da Grant 5-U24-DK059637-10 al Centro Fenotipizzazione mouse Vanderbilt Metabolica.

<ol>
	<li>Ayala, J. E., Bracy, D. P., McGuinness, O. P., Wasserman, D. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Considerations+in+the+design+of+hyperinsulinemic-euglycemic+clamps+in+the+conscious+mouse.">Considerations in the design of hyperinsulinemic-euglycemic clamps in the conscious mouse.</a> Diabetes. 55, 390-397 (2006).</li><li>Berglund, E. D., Li, C. Y., Poffenberger, G., Ayala, J. E., Fueger, P. T., Willis, S. E., Jewell, M. M., Powers, A. C., Wasserman, D. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glucose+metabolism+in+vivo+in+four+commonly+used+inbred+mouse+strains.">Glucose metabolism in vivo in four commonly used inbred mouse strains.</a> Diabetes. 57, 1790-1799 (2008).</li><li>Niswender, K. D., Shiota, M., Postic, C., Cherrington, A. D., Magnuson, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+increased+glucokinase+gene+copy+number+on+glucose+homeostasis+and+hepatic+glucose+metabolism.">Effects of increased glucokinase gene copy number on glucose homeostasis and hepatic glucose metabolism.</a> J. Biol. Chem. 272, 22570-22575 (1997).</li><li>Kim, H. J., Higashimori, T., Park, S. Y., Choi, H., Dong, J., Kim, Y. J., Noh, H. L., Cho, Y. R., Cline, G., Kim, Y. B., Kim, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+effects+of+interleukin-6+and+-10+on+skeletal+muscle+and+liver+insulin+action+in+vivo.">Differential effects of interleukin-6 and -10 on skeletal muscle and liver insulin action in vivo.</a> Diabetes. 53, 1060-1067 (2004).</li><li>Kim, J. K., Fillmore, J. J., Chen, Y., Yu, C., Moore, I. K., Pypaert, M., Lutz, E. P., Kako, Y., Velez-Carrasco, W., Goldberg, I. J., Breslow, J. L., Shulman, G. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue-specific+overexpression+of+lipoprotein+lipase+causes+tissue-specific+insulin+resistance.">Tissue-specific overexpression of lipoprotein lipase causes tissue-specific insulin resistance.</a> Proc. Natl. Acad. Sci. U. S. A. 98, 7522-7527 (2001).</li><li>Kim, J. K., Fillmore, J. J., Gavrilova, O., Chao, L., Higashimori, T., Choi, H., Kim, H. J., Yu, C., Chen, Y., Qu, X., Haluzik, M., Reitman, M. L., Shulman, G. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+effects+of+rosiglitazone+on+skeletal+muscle+and+liver+insulin+resistance+in+A-ZIP/F-1+fatless+mice.">Differential effects of rosiglitazone on skeletal muscle and liver insulin resistance in A-ZIP/F-1 fatless mice.</a> Diabetes. 52, 1311-1318 (2003).</li><li>Kim, J. K., Fillmore, J. J., Sunshine, M. J., Albrecht, B., Higashimori, T., Kim, D. W., Liu, Z. X., Soos, T. J., Cline, G. W., O'Brien, W. R., Littman, D. R., Shulman, G. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PKC-theta+knockout+mice+are+protected+from+fat-induced+insulin+resistance.">PKC-theta knockout mice are protected from fat-induced insulin resistance.</a> J. Clin. Invest. 114, 823-827 (2004).</li><li>Kim, J. K., Gavrilova, O., Chen, Y., Reitman, M. L., Shulman, G. 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W., Enerback, S., Shulman, G. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adipocyte-specific+overexpression+of+FOXC2+prevents+diet-induced+increases+in+intramuscular+fatty+acyl+CoA+and+insulin+resistance.">Adipocyte-specific overexpression of FOXC2 prevents diet-induced increases in intramuscular fatty acyl CoA and insulin resistance.</a> Diabetes. 54, 1657-1663 (2005).</li><li>Kim, J. K., Kim, Y. J., Fillmore, J. J., Chen, Y., Moore, I., Lee, J., Yuan, M., Li, Z. W., Karin, M., Perret, P., Shoelson, S. E., Shulman, G. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prevention+of+fat-induced+insulin+resistance+by+salicylate.">Prevention of fat-induced insulin resistance by salicylate.</a> J. Clin. Invest. 108, 437-446 (2001).</li><li>Kim, J. K., Michael, P. r. e. v. i. s., Peroni, S. F., Mauvais-Jarvis, O. D., Neschen, F., Kahn, S., Kahn, B. B., R, C., Shulman, G. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Redistribution+of+substrates+to+adipose+tissue+promotes+obesity+in+mice+with+selective+insulin+resistance+in+muscle.">Redistribution of substrates to adipose tissue promotes obesity in mice with selective insulin resistance in muscle.</a> J. Clin. Invest. 105, 1791-1797 (2000).</li><li>Kim, J. K., Zisman, A., Fillmore, J. J., Peroni, O. D., Kotani, K., Perret, P., Zong, H., Dong, J., Kahn, C. R., Kahn, B. B., Shulman, G. 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Invest. 108, 153-160 (2001).</li><li>Haluzik, M., Gavrilova, O., LeRoith, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Peroxisome+proliferator-activated+receptor-alpha+deficiency+does+not+alter+insulin+sensitivity+in+mice+maintained+on+regular+or+high-fat+diet:+hyperinsulinemic-euglycemic+clamp+studies.">Peroxisome proliferator-activated receptor-alpha deficiency does not alter insulin sensitivity in mice maintained on regular or high-fat diet: hyperinsulinemic-euglycemic clamp studies.</a> Endocrinology. 145, 1662-1667 (2004).</li><li>Haluzik, M., Yakar, S., Gavrilova, O., Setser, J., Boisclair, Y., LeRoith, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insulin+resistance+in+the+liver-specific+IGF-1+gene-deleted+mouse+is+abrogated+by+deletion+of+the+acid-labile+subunit+of+the+IGF-binding+protein-3+complex:+relative+roles+of+growth+hormone+and+IGF-1+in+insulin+resistance.">Insulin resistance in the liver-specific IGF-1 gene-deleted mouse is abrogated by deletion of the acid-labile subunit of the IGF-binding protein-3 complex: relative roles of growth hormone and IGF-1 in insulin resistance.</a> Diabetes. 52, 2483-2489 (2003).</li><li>Haluzik, M. M., Lacinova, Z., Dolinkova, M., Haluzikova, D., Housa, D., Horinek, A., Vernerova, Z., Kumstyrova, T., Haluzik, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improvement+of+insulin+sensitivity+after+peroxisome+proliferator-activated+receptor-alpha+agonist+treatment+is+accompanied+by+paradoxical+increase+of+circulating+resistin+levels.">Improvement of insulin sensitivity after peroxisome proliferator-activated receptor-alpha agonist treatment is accompanied by paradoxical increase of circulating resistin levels.</a> Endocrinology. 147, 4517-4524 (2006).</li><li>Kim, H., Haluzik, M., Asghar, Z., Yau, D., Joseph, J. W., Fernandez, A. M., Reitman, M. L., Yakar, S., Stannard, B., Heron-Milhavet, L., Wheeler, M. B., LeRoith, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Peroxisome+proliferator-activated+receptor-alpha+agonist+treatment+in+a+transgenic+model+of+type+2+diabetes+reverses+the+lipotoxic+state+and+improves+glucose+homeostasis.">Peroxisome proliferator-activated receptor-alpha agonist treatment in a transgenic model of type 2 diabetes reverses the lipotoxic state and improves glucose homeostasis.</a> Diabetes. 52, 1770-1778 (2003).</li><li>Deibert, D. C., DeFronzo, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epinephrine-induced+insulin+resistance+in+man.">Epinephrine-induced insulin resistance in man.</a> J. Clin. Invest. 65, 717-721 (1980).</li><li>Rizza, R. A., Cryer, P. E., Haymond, M. W., Gerich, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adrenergic+mechanisms+for+the+effects+of+epinephrine+on+glucose+production+and+clearance+in+man.">Adrenergic mechanisms for the effects of epinephrine on glucose production and clearance in man.</a> J. Clin. Invest. 65, 682-689 (1980).</li><li>Nunemaker, C. S., Wasserman, D. H., McGuinness, O. P., Sweet, I. R., Teague, J. C., Satin, L. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insulin+secretion+in+the+conscious+mouse+is+biphasic+and+pulsatile.">Insulin secretion in the conscious mouse is biphasic and pulsatile.</a> Am. J. Physiol. Endocrinol. Metab. 290, 523-529 (2006).</li><li>Nunemaker, C. S., Zhang, M., Wasserman, D. H., McGuinness, O. P., Powers, A. C., Bertram, R., Sherman, A., Satin, L. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Individual+mice+can+be+distinguished+by+the+period+of+their+islet+calcium+oscillations:+is+there+an+intrinsic+islet+period+that+is+imprinted+in+vivo.">Individual mice can be distinguished by the period of their islet calcium oscillations: is there an intrinsic islet period that is imprinted in vivo.</a> Diabetes. 54, 3517-3522 (2005).</li><li>Halter, J. B., Beard, J. C., Jr, P. o. r. t. e., D, . <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Islet+function+and+stress+hyperglycemia:+plasma+glucose+and+epinephrine+interaction.">Islet function and stress hyperglycemia: plasma glucose and epinephrine interaction.</a> Am. J. Physiol. 247, 47-52 (1984).</li><li>Jacobson, L., Ansari, T., McGuinness, O. 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P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glucocorticoid-deficient+corticotropin-releasing+hormone+knockout+mice+maintain+glucose+requirements+but+not+autonomic+responses+during+repeated+hypoglycemia.">Glucocorticoid-deficient corticotropin-releasing hormone knockout mice maintain glucose requirements but not autonomic responses during repeated hypoglycemia.</a> Am. J. Physiol. Endocrinol. Metab. 291, 15-22 (2006).</li><li>Ayala, J. E., Bracy, D. P., James, F. D., Julien, B. M., Wasserman, D. H., Drucker, D. 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Nessun conflitto di interessi dichiarati.

Il iperinsulinemico-euglicemico morsetto, o pinza insulina, è largamente considerato il &quot;gold standard&quot; metodo per valutare l&#39;azione dell&#39;insulina in vivo. Questa tecnica è stata applicata a diverse specie tra cui gli esseri umani, cani, ratti e topi. Dato il numero crescente di modelli di topi transgenici per i disturbi metabolici, la miniaturizzazione della tecnica per l&#39;utilizzo nel topo ha fornito significativi progressi alla ricerca del metabolismo. Mentre i concetti dietro il fermo di insulina sono semplici, in pratica ci sono diversi approcci per l&#39;esecuzione di esperimenti di clamp insulina. Questo non è un punto banale, dal momento che il modo in cui viene eseguito l&#39;esperimento interessa risultati ottenuti 1. Qui vi presentiamo il protocollo utilizzato dal MMPC Vanderbilt. La distinzione fondamentale tra il nostro protocollo e quella di altri è che usiamo un catetere arterioso per ottenere campioni di sangue. Ciò è in contrasto con l&#39;approccio più diffuso di OBTaining campioni di sangue da troncare la punta della coda 4, 7, 11, 12, 14-17. Il vantaggio di campionamento da un catetere arterioso è che l&#39;esperimento è condotto in un topo consapevole e sfrenato. Campionamento dalla coda spesso richiede moderazione e aumenta gli indici di stress quando i campioni di sangue di grandi dimensioni vengono acquisiti 1. Ormoni dello stress stimola la produzione endogena di glucosio e mettere in pericolo lo smaltimento del glucosio 18, 19, potenzialmente dando l&#39;apparenza di un fenotipo insulino-resistenti. Campionamento dalla coda mozzata potrebbe richiedere speciali Cura degli animali e del Comitato Istituzionale l&#39;approvazione Usa per la sua natura stressante. La procedura di cateterismo arterioso è stato sviluppato per evitare lo stress al mouse di separare gli coda. Un aspetto fondamentale di realizzare pinze insulina è la capacità di mantenere euglicemia. Non ci sono algoritmi in grado di predire correttamente come il GIR deve essere regolato sulla base di letture di glucosio nel sangue. Come la chirurgia,personale che esegue esperimenti di clamp insulina diventare abili nel mantenere euglicemia ragionevole solo attraverso l&#39;esperienza. E &#39;importante notare che a causa del loro tasso metabolico più elevato i dati ottenuti dagli studi del mouse sarà intrinsecamente rumorosa. Questo rende la presentazione completa dei dati, compresi i corsi tempo di glucosio e GIR e valori assoluti di insulina plasmatica, Endora, Rd e Rg cruciale per la capacità di qualsiasi lettore di interpretare i risultati. L&#39;elevato tasso di glucosio nel flusso del mouse (circa 5 volte superiore al tasso nell&#39;uomo) garantisce un&#39;alta frequenza di campionamento di glucosio. Mentre il volume di sangue del mouse è limitato, una frequenza di campionamento minima di una volta ogni 10 minuti è necessario essere certi che un morsetto adeguato è stato raggiunto. Come mostrato nella Figura 4, i livelli di insulina morsetto può essere diversa tra i gruppi. Fattori come la dieta interventi, manipolazioni transgeniche o le differenze nei ceppi sfondo può influenzare faslivelli di insulina Ting, che possono influenzare i livelli di insulina in seguito morsetto. Interpretazione dei risultati quando i livelli di insulina sono diversi morsetto può essere problematico. Questo può essere affrontato sperimentalmente eseguendo esperimenti pilota di selezionare velocità di infusione di insulina che consentano di raggiungere livelli equivalenti morsetto di insulina tra i gruppi. In alternativa, la somatostatina può essere utilizzato per inibire l&#39;ormone della secrezione pancreatica, e l&#39;insulina e il glucagone può essere sostituito a tassi sperimentalmente controllati. Quest&#39;ultimo approccio è più comunemente fatto in fascette di insulina in ratti che topi. Se questi approcci sperimentali non vengono presi, allo steady-state GIR può essere normalizzata al livello di insulina morsetto, o un indice di sensibilità insulinica (S I) può essere ricavato da dati morsetto come S = I GIR / (G • ΔI), dove G è allo steady-state concentrazione di glucosio e ΔI è la differenza tra le concentrazioni di insulina a digiuno e morsetto. Un assunto con entrambi gli approcci è che il livello di insulina morsetto raggiunto èall&#39;interno del campo in cui la sensibilità all&#39;insulina è linearmente correlata al livello di insulina a seconda del gruppo oggetto di studio. Questa seconda ipotesi non può applicare quando si confrontano insulino-resistenti e gruppi sensibili all&#39;insulina. Idealmente, una dose di insulina curva di risposta dovrebbe essere generato per selezionare l&#39;appropriata infusione di insulina. Tuttavia, a causa della necessità di ulteriori esperimenti, ciò avviene raramente. La versatilità fornita da cateterismo arterioso si estende al di là di approcci sperimentali morsetti euglicemico. Per esempio, fascette iperglicemia, in cui viene infuso glucosio a tasso variabile per mantenere l&#39;iperglicemia rispetto alla glicemia a digiuno, può essere utilizzato per valutare la funzione endogena del pancreas in vivo 2, 20, 21. La misura della secrezione di insulina prima fase nel corso di questo test richiede l&#39;acquisizione frequente di campioni di sangue (cioè ogni 2-5 minuti), che non è possibile ottenere campioni quando dalla punta della coda. Inoltre,catecolamine elevato relativi al campionamento coda può mettere in pericolo la secrezione di insulina e migliorare la secrezione di glucagone 22. Il protocollo morsetto insulina può anche essere modificato per consentire livelli di glucosio a cadere a ipoglicemia rispetto per valutare contro-regolatore di risposta 2, 23, 24. Cateterismo arterioso può essere utilizzato anche per valutare le dinamiche del metabolismo del glucosio durante l&#39;esercizio fisico 25-30. Questo è decisamente vantaggioso rispetto agli approcci convenzionali condotto in momenti singoli pre-e post-esercizio o negli isolati ex vivo muscoli. Le tecniche qui presentate può essere utilizzato anche per valutare non solo il glucosio, ma anche il metabolismo degli acidi grassi 31.

hyperinsulinemic-euglycemic clamps in conscious, unrestrained mice

Diabete di tipo 2 è caratterizzato da un difetto in azione dell&#39;insulina. Il iperinsulinemico-euglicemico morsetto, o pinza insulina, è largamente considerato il &quot;gold standard&quot; metodo per valutare l&#39;azione dell&#39;insulina in vivo. Nel corso di un morsetto di insulina, iperinsulinemia è ottenuta da una infusione di insulina costante. Euglicemia è mantenuto tramite un infusione di glucosio concomitante ad un tasso variabile. Questa variabile velocità di infusione glucosio (GIR) è determinato dalla misurazione della glicemia a intervalli brevi durante tutto l&#39;esperimento e regolando di conseguenza il GIR. Il GIR è indicativo di tutto il corpo l&#39;azione dell&#39;insulina, come i topi con l&#39;azione dell&#39;insulina maggiore richiedono una maggiore GIR. Il morsetto di insulina può incorporare somministrazione di isotopica 2 [14 C] desossiglucosio per valutare tessuto-specifici assorbimento di glucosio e [3 - 3 H] glucosio per valutare la capacità dell&#39;insulina di sopprimere il tasso di comparsa di glucosio endogeno (Endora), un marker di produzione epatica di glucosio e di stimolare latasso di tutto il corpo scomparsa di glucosio (Rd). La miniaturizzazione del morsetto insulina per l&#39;uso in modelli murini di malattie genetiche metaboliche ha portato a progressi significativi nella ricerca sul diabete. Metodi per l&#39;esecuzione pinze insulina variano tra laboratori. E &#39;importante notare che il modo in cui viene eseguito un clamp di insulina possono influenzare significativamente i risultati ottenuti. Abbiamo pubblicato una valutazione completa dei diversi approcci a svolgere morsetti insulina nei topi coscienti 1 nonché una valutazione della risposta metabolica dei quattro ceppi del mouse comunemente usata inbred con tecniche varie morsetto 2. Qui vi presentiamo un protocollo per l&#39;esecuzione di morsetti insulina cosciente, topi sfrenato sviluppato dal mouse Vanderbilt Metabolica Fenotipizzazione Center (MMPC; URL: www.mc.vanderbilt.edu / MMPC). Ciò include una descrizione del metodo per impiantare cateteri utilizzati durante il morsetto insulina. Il protocollo impiegato dalVanderbilt MMPC utilizza un esclusivo doppio catetere sistema a 3. Un catetere viene inserito nella vena giugulare per infusioni. Un catetere è inserito il secondo in arteria carotide, che consente il prelievo di sangue, senza la necessità di limitare o gestire il mouse. Questa tecnica fornisce un significativo vantaggio per il metodo più comune per ottenere campioni di sangue durante le fascette di insulina che è quello di campione dalla punta della coda mozzata. A differenza di questo ultimo metodo, il campionamento di un catetere arterioso non è stressante al mouse 1. Abbiamo inoltre descrivere i metodi per l&#39;utilizzo di infusi traccianti isotopici per valutare tessuto-specifica azione dell&#39;insulina. Abbiamo anche fornire orientamenti per la presentazione adeguata dei risultati ottenuti dai morsetti insulina.

Watch this Scientific Journal Video about Hyperinsulinemic-euglycemic Clamps in Conscious, Unrestrained Mice at JoVE.com

Hyperinsulinemic-euglycemic Clamps in Conscious, Unrestrained Mice

Il iperinsulinemico-euglicemico morsetto, o pinza insulina, è il gold standard per valutare l&#39;azione dell&#39;insulina<em&gt; In vivo</em&gt;. Un metodo per l&#39;esecuzione di fascette di insulina nei topi è descritto. Ciò include un metodo per cateterismo arterioso che permette esperimenti da eseguire in coscienza, i topi sfrenato con un minimo sforzo.

Iperinsulinemico-euglicemico Morsetti in Cosciente, Mouse sfrenato

Type 2 diabetes is characterized by a defect in insulin action. The hyperinsulinemic-euglycemic clamp, or insulin clamp, is widely considered the "gold ...

hyperinsulinemic-euglycemic-clamps-in-conscious-unrestrained-mice

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JoVE Journal

Medicine

94.1K Views.  Sanford-Burnham Medical Research Institute at Lake Nona. Il iperinsulinemico-euglicemico morsetto, o pinza insulina, è il gold standard per valutare l'azione dell'insulina In vivo. Un metodo per l'esecuzione di fascette di insulina nei topi è descritto. Ciò include un metodo per cateterismo arterioso che permette esperimenti da eseguire in coscienza, i topi sfrenato con un minimo sforzo.

Video: Hyperinsulinemic-euglycemic Clamps in Conscious, Unrestrained Mice

Transthoracic Echocardiography in Mice

In recent years, murine models have become the primary avenue for studying the molecular mechanisms of cardiac dysfunction resulting from changes in gene expression. Transgenic and gene targeting methods can be used to generate mice with altered cardiac size and function,1-3 and as a result, in vivo techniques are needed to evaluate their cardiac phenotype. Transthoracic echocardiography, pulse wave Doppler (PWD), and tissue Doppler imaging (TDI) can be used to provide dimensional measurements of the mouse heart and to quantify the degree of cardiac systolic and diastolic performance. Two-dimensional imaging is used to detect abnormal anatomy or movements of the left ventricle, whereas M-mode echo is used for quantification of cardiac dimensions and contractility.4,5 In addition, PWD is used to quantify localized velocity of turbulent flow,6 whereas TDI is used to measure the velocity of myocardial motion.7 Thus, transthoracic echocardiography offers a comprehensive method for the noninvasive evaluation of cardiac function in mice.

Transthoracic echocardiography offers a noninvasive method for the evaluation of cardiac function in mice. A combination of ultrasound and Doppler imaging modalities can be used to obtain dimensional measurements of the heart and intracardiac blood flow, which together provide an assessment of cardiac systolic and diastolic performance.

L&#39;ecocardiografia transtoracica in topi

In recent years, murine models have become the primary avenue for studying the molecular mechanisms of cardiac dysfunction resulting from changes in gene ...

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Hyperinsulinemic-Euglycemic Clamp in the Conscious Rat

Type 2 diabetes (T2D) is rapidly rising in prevalence. Characterized by either inadequate insulin production or the inability to utilize insulin produced, T2D results in elevated blood glucose levels. The "gold-standard" in assessing insulin sensitivity is a hyperinsulinemic-euglycemic clamp or insulin clamp. In this procedure, insulin is infused at a constant rate resulting in a drop in blood glucose. To maintain blood glucose at a constant level, exogenous glucose (D50) is infused into the venous circulation. The amount of glucose infused to maintain homeostasis is indicative of insulin sensitivity. Here, we show the basic clamp procedure in the chronically catheterized, unrestrained, conscious rat. This model allows blood to be collected with minimal stress to the animal. Following the induction of anesthesia, a midline incision is made and the left common carotid artery and right jugular vein are catheterized. Inserted catheters are flushed with heparinized saline, then exteriorized and secured. Animals are allowed to recover for 4-5 days prior to experiments, with weight gain monitored daily. Only those animals who regain weight to pre-surgery levels are used for experiments. On the day of the experiment, rats are fasted and connected to pumps containing insulin and D50. Baseline glucose is assessed from the arterial line and used a benchmark throughout the experiment (euglycemia). Following this, insulin is infused at a constant rate into the venous circulation. To match the drop in blood glucose, D50 is infused. If the rate of D50 infusion is greater than the rate of uptake, a rise in glucose will occur. Similarly, if the rate is insufficient to match whole body glucose uptake, a drop will occur. Titration of glucose continues until stable glucose readings are achieved. Glucose levels and glucose infusion rates during this stable period are recorded and reported. Results provide an index of whole body insulin sensitivity. The technique can be refined to meet specific experimental requirements. It is further enhanced by the use of radioactive tracers that can determine tissue specific insulin-stimulated glucose uptake as well as whole body glucose turnover.

The hyperinsulinemic-euglycemic clamp is the "gold standard" for the assessment of insulin action. Insulin is infused at a constant rate stimulating glucose uptake. The amount of exogenous glucose infused to counter this drop is indicative of insulin sensitivity. Here the procedure is performed on a conscious, unrestrained rat.

Iperinsulinemico-euglicemico pinza nei topi

Type 2 diabetes (T2D) is rapidly rising in prevalence. Characterized by either inadequate insulin production or the inability to utilize insulin produced, ...

Controlled Cervical Laceration Injury in Mice

Use of genetically modified mice enhances our understanding of molecular mechanisms underlying several neurological disorders such as a spinal cord injury (SCI). Freehand manual control used to produce a laceration model of SCI creates inconsistent injuries often associated with a crush or contusion component and, therefore, a novel technique was developed. Our model of cervical laceration SCI has resolved inherent difficulties with the freehand method by incorporating 1) cervical vertebral stabilization by vertebral facet fixation, 2) enhanced spinal cord exposure, and 3) creation of a reproducible laceration of the spinal cord using an oscillating blade with an accuracy of &plusmn;0.01 mm in depth without associated contusion. Compared to the standard methods of creating a SCI laceration such as freehand use of a scalpel or scissors, our method has produced a consistent lesion. This method is useful for studies on axonal regeneration of corticospinal, rubrospinal, and dorsal ascending tracts.

A novel technique to create a reproducible in vivo model of cervical spinal cord laceration injury in the mouse is described. This technique is based on spine stabilization by fixation of the cervical facets and laceration of the spinal cord using an oscillating blade with an accuracy of &plusmn;0.01 mm.

Controllata cervicale lesioni lacerazione nei topi

Use of genetically modified mice enhances our  understanding of molecular mechanisms underlying several neurological disorders  such as a spinal cord ...

Carotid Artery Infusions for Pharmacokinetic and Pharmacodynamic Analysis of Taxanes in Mice

When proposing the use of a drug, drug combination, or drug delivery into a novel system, one must assess the pharmacokinetics of the drug in the study model. As the use of mouse models are often a vital step in preclinical drug discovery and drug development1-8, it is necessary to design a system to introduce drugs into mice in a uniform, reproducible manner. Ideally, the system should permit the collection of blood samples at regular intervals over a set time course. The ability to measure drug concentrations by mass-spectrometry, has allowed investigators to follow the changes in plasma drug levels over time in individual mice1, 9, 10. In this study, paclitaxel was introduced into transgenic mice as a continuous arterial infusion over three hours, while blood samples were simultaneously taken by retro-orbital bleeds at set time points. Carotid artery infusions are a potential alternative to jugular vein infusions, when factors such as mammary tumors or other obstructions make jugular infusions impractical. Using this technique, paclitaxel concentrations in plasma and tissue achieved similar levels as compared to jugular infusion. In this tutorial, we will demonstrate how to successfully catheterize the carotid artery by preparing an optimized catheter for the individual mouse model, then show how to insert and secure the catheter into the mouse carotid artery, thread the end of the catheter out through the back of the mouse&#8217;s neck, and hook the mouse to a pump to deliver a controlled rate of drug influx. Multiple low volume retro-orbital bleeds allow for analysis of plasma drug concentrations over time.

This method was developed with the goal of delivering a steady drug solution via the carotid artery, to assess the pharmacokinetics of novel drugs in mouse models.

Infusi carotide di farmacocinetica e di farmacodinamica Analisi dei taxani nei topi

When proposing the use of a drug, drug combination, or drug delivery into a novel system, one must assess the pharmacokinetics of the drug in the study ...

Heterotopic Cervical Heart Transplantation in Mice

The heterotopic cervical heart transplantation in mice is a valuable tool in transplant and cardiovascular research. The cuff technique greatly simplifies this model by avoiding challenging suture anastomoses of small vessels thereby reducing warm ischemia time. In comparison to abdominal graft implantation the cervical model is less invasive and the implanted graft is easily accessible for further follow-up examinations. Anastomoses are performed by pulling the ascending aorta of the graft over the cuff with the recipient&#8217;s common carotid artery and by pulling the main pulmonary artery over the cuff with the external jugular vein. Selection of appropriate cuff size and complete mobilization of the vessels are important for successful revascularization. Ischemia-reperfusion (I/R) injury can be minimized by perfusing the graft with a cardioplegic solution and by hypothermia. In this article, we provide technical details for a simplified and improved cuff technique, which should allow surgeons with basic microsurgical skills to perform the procedure with a high success rate.

The cuff technique shortens and facilitates the model of heterotopic cervical heart transplantation in mice by avoiding technically challenging suture anastomoses of small vessels. The technical details shown in this video paper should allow researches to establish this model in their laboratories.

Eterotopico cervicale trapianto cardiaco nei topi

The heterotopic cervical heart transplantation in mice is a valuable tool in transplant and cardiovascular research. The cuff technique greatly simplifies ...

Transcutaneous Assessment of Renal Function in Conscious Rodents

Glomerular filtration rate (GFR) is the gold standard to assess overall kidney function. However, traditional methods to evaluate GFR are cumbersome and time-consuming. In addition, serial blood or urine samples are required, with the associated stress for the experimental animals. A recent technique significantly reduces the investment in time and resources, minimizing the invasiveness and the animal stress, but being equally valid as the traditional approaches. The method measures transcutaneously renal function. Using an optical device and the exogenous renal marker fluorescein isothiocyanate (FITC)-sinistrin, this technique is capable of measuring the elimination kinetics of the marker through the skin. With neither blood nor urine samples nor the associated laboratory assays needed, the results of the transcutaneous measurement are almost instantaneously available. The method has been already validated in different species and successfully applied in several models of renal pathology. Moreover, due to its minimally invasive characteristics, it is suitable for sequential measurements within the same animal. Here is provided a detailed protocol to carry out the transcutaneous assessment of renal function in rodents.

Determination of glomerular filtration rate (GFR) is the gold standard to assess overall kidney function. However, traditional procedures to measure this parameter are cumbersome and require a large investment of time. Here we describe a faster and minimally invasive method to determinate GFR transcutaneously.

La valutazione transcutanea della funzione renale nei roditori Conscious

Glomerular filtration rate (GFR) is the gold standard to assess overall kidney function. However, traditional methods to evaluate GFR are cumbersome and ...

Novel Approach for Simultaneous Recording of Renal Sympathetic Nerve Activity and Blood Pressure with Intravenous Infusion in Conscious, Unrestrained Mice.

Renal sympathetic nerves contribute significantly to both physiological and pathophysiological phenomena. Evaluating renal sympathetic nerve activity (RSNA) is of great interest in many areas of research such as chronic kidney disease, hypertension, heart failure, diabetes and obesity. Unequivocal assessment of the role of the sympathetic nervous system is thus imperative for proper interpretation of experimental results and understanding of disease processes. RSNA has been traditionally measured in anesthetized rodents, including mice. However, mice usually exhibit very low systemic blood pressure and hemodynamic instability for several hours during anesthesia and surgery. Meaningful interpretation of RSNA is confounded by this non-physiological state, given the intimate relationship between sympathetic nervous tone and cardiovascular status. To address this limitation of traditional approaches, we developed a new method for measuring RSNA in conscious, freely-moving mice. Mice were chronically instrumented with radio-telemeters for continuous monitoring of blood pressure as well as a jugular venous infusion catheter and custom-designed bipolar electrode for direct recording of RSNA. Following a 48-72 hour recovery period, survival rate was 100% and all mice behaved normally. At this time-point, RSNA was successfully recorded in 80% of mice, with viable signals acquired up to 4 and 5 days post-surgery in 70% and 50% of mice, respectively. Physiological blood pressures were recorded in all mice (116&plusmn;2 mmHg; n=10). Recorded RSNA increased with eating and grooming, as well-established in the literature. Furthermore, RSNA was validated by ganglionic blockade and modulation of blood pressure with pharmacological agents. Herein, an effective and manageable method for clear recording of RSNA in conscious, freely-moving mice is described.

Anesthetized mice exhibit non-physiological systemic blood pressure, which precludes meaningful assessment of autonomic tone given the intimate relationship between blood pressure and the autonomic nervous system. Thus, a novel method to simultaneously record renal sympathetic nerve activity and blood pressure with intravenous infusion in conscious mice is outlined.

Nuovo approccio per la registrazione simultanea di attività simpatica renale del nervo e pressione del sangue con l'infusione endovenosa in consapevole, topi sfrenati.

Renal sympathetic nerves contribute significantly to both physiological and pathophysiological phenomena. Evaluating renal sympathetic nerve activity ...

Assessment of Respiratory Function in Conscious Mice by Double-chamber Plethysmography

Air volume changes created by a conscious subject breathing spontaneously within a body box are at the basis of plethysmography, a technique used to non-invasively assess some features of the respiratory function in humans as well as in laboratory animals. The present article focuses on the application of the double-chamber plethysmography (DCP) in small animals. It provides background information on the methodology as well as a detailed step-by-step procedure to successfully assess respiratory function in conscious, spontaneously breathing animals in a non-invasive manner. The DCP can be used to monitor the respiratory function of multiple animals in parallel, as well as to identify changes induced by aerosolized substances over a chosen time period and in a repeated manner. Experiments on control and allergic mice are used herein to demonstrate the utility of the technique, explain the associated outcome parameters, as well as to discuss the related advantages and shortcomings. Overall, the DCP provides valid and theoretically sound readouts that can be trusted to evaluate the respiratory function of conscious small animals both at baseline and after challenges with aerosolized substances.

The objective of the present article is to provide a detailed description of the recommended procedures to evaluate respiratory function in conscious mice by double-chamber plethysmography.

Valutazione della funzione respiratoria in topi cosciente da doppia camera pletismografia

Air volume changes created by a conscious subject breathing spontaneously within a body box are at the basis of plethysmography, a technique used to ...

Repeated Orotracheal Intubation in Mice

The literature describes several methods for mouse intubation that either require visualization of the glottis through the oral cavity or incision in the ventral neck for direct confirmation of cannula placement in the trachea. The relative difficulty or the tissue trauma induced to the subject by such procedures can be an impediment to an investigator&#8217;s ability to perform longitudinal studies. This article illustrates a technique in which physical manipulation of the mouse following the use of a depilatory to remove hair from the ventral neck permits transcutaneous visualization of the trachea for orotracheal intubation regardless of degree of skin pigmentation. This method is innocuous to the subject and easily achieved with a limited understanding of murine anatomy. This refined approach facilitates repeated intubation, which may be necessary for monitoring progression of disease or instillation of treatments. Using this method may result in a reduction of the number of animals and technical skill required to measure lung function in mouse models of respiratory disease.

The goal of this article is to describe a refined method of intubation of the laboratory mouse. The method is noninvasive and, therefore, ideal for studies that require serial monitoring of respiratory function and/or instillation of treatments into the lung.

Intubazione orotrachea ripetuta nei topi

The literature describes several methods for mouse intubation that either require visualization of the glottis through the oral cavity or incision in the ...

Implantation of Combined Telemetric ECG and Blood Pressure Transmitters to Determine Spontaneous Baroreflex Sensitivity in Conscious Mice

Blood pressure (BP) and heart rate (HR) are both controlled by the autonomic nervous system (ANS) and are closely intertwined due to reflex mechanisms. The baroreflex is a key homeostatic mechanism to counteract acute, short-term changes in arterial BP and to maintain BP in a relatively narrow physiological range. BP is sensed by baroreceptors located in the aortic arch and carotid sinus. When BP changes, signals are transmitted to the central nervous system and are then communicated to the parasympathetic and sympathetic branches of the autonomic nervous system to adjust HR. A rise in BP causes a reflex decrease in HR, a drop in BP causes a reflex increase in HR.
Baroreflex sensitivity (BRS) is the quantitative relationship between changes in arterial BP and corresponding changes in HR. Cardiovascular diseases are often associated with impaired baroreflex function. In various studies reduced BRS has been reported in e.g., heart failure, myocardial infarction, or coronary artery disease. 
Determination of BRS requires information from both BP and HR, which can be recorded simultaneously using telemetric devices. The surgical procedure is described beginning with the insertion of the pressure sensor into the left carotid artery and positioning of its tip in the aortic arch to monitor arterial pressure followed by the subcutaneous placement of the transmitter and ECG electrodes. We also describe postoperative intensive care and analgesic management. After a two-week period of post-surgery recovery long-term ECG and BP recordings are performed in conscious and unrestrained mice. Finally, we include examples of high-quality recordings and the analysis of spontaneous baroreceptor sensitivity using the sequence method.

The baroreflex is a heart-rate regulation mechanism by the autonomic nervous system in response to blood-pressure changes. We describe a surgical technique to implant telemetry transmitters for continuous and simultaneous measurement of electrocardiogram and blood pressure in mice. This can determine spontaneous baroreflex sensitivity, an important prognostic marker for cardiovascular disease.

Impianto combinato di ECG telemetrico e trasmettitori di pressione sanguigna per determinare la sensibilità baroriflessa spontanea in topi coscienti

Blood pressure (BP) and heart rate (HR) are both controlled by the autonomic nervous system (ANS) and are closely intertwined due to reflex mechanisms. ...