The authors would like to thank the volunteers for their participation in these studies and the surgical staff at the Boston Medical Center for providing adipose tissue biopsies. Dr. Gokce is supported by National Institutes of Health (NIH) grants HL081587, HL114675, and HL126141. Dr. Farb is supported by NIH grant K23 HL135394.

The protocol and examples described here were approved by Boston University School of Medicine Institutional Review Board (IRB, protocol #H-25644) and were conducted in accordance with the Declaration of Helsinki. All subjects provided written informed consent before participation.
1. Preparation of Solutions and Micro-glass Cannulas
<ol>
	<li>Prepare the 4-2-hydrosyethyl-1-piperazineethanesulfonic acidic saline (HEPES) solution. For 1 L, dissolve 8.059 g NaCl, 0.298 g KCl, 0.296 g MgSO...

<ol>
	<li>Schubert, R., Mulvany, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+myogenic+response:+established+facts+and+attractive+hypotheses.">The myogenic response: established facts and attractive hypotheses.</a> Clin Sci (Lond). 96 (4), 313-326 (1999).</li><li>Jadeja, R. N., Rachakonda, V., Bagi, Z., Khurana, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessing+Myogenic+Response+and+Vasoactivity+In+Resistance+Mesenteric+Arteries+Using+Pressure+Myography.">Assessing Myogenic Response and Vasoactivity In Resistance Mesenteric Arteries Using Pressure Myography.</a> J Vis Exp. (101), e50997 (2015).</li><li>Gutterman, D. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Human+Microcirculation:+Regulation+of+Flow+and+Beyond.">The Human Microcirculation: Regulation of Flow and Beyond.</a> Circ Res. 118 (1), 157-172 (2016).</li><li>Fuster, J. J., Ouchi, N., Gokce, N., Walsh, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Obesity-Induced+Changes+in+Adipose+Tissue+Microenvironment+and+Their+Impact+on+Cardiovascular+Disease.">Obesity-Induced Changes in Adipose Tissue Microenvironment and Their Impact on Cardiovascular Disease.</a> Circ Res. 118 (11), 1786-1807 (2016).</li><li>Farb, M. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduced+adipose+tissue+inflammation+represents+an+intermediate+cardiometabolic+phenotype+in+obesity.">Reduced adipose tissue inflammation represents an intermediate cardiometabolic phenotype in obesity.</a> J Am Coll Cardiol. 58 (3), 232-237 (2011).</li><li>Farb, M. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=WNT5A-JNK+regulation+of+vascular+insulin+resistance+in+human+obesity.">WNT5A-JNK regulation of vascular insulin resistance in human obesity.</a> Vasc Med. 21 (6), 489-496 (2016).</li><li>Durand, M. J., Phillips, S. A., Widlansky, M. E., Otterson, M. F., Gutterman, D. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+vascular+renin-angiotensin+system+contributes+to+blunted+vasodilation+induced+by+transient+high+pressure+in+human+adipose+microvessels.">The vascular renin-angiotensin system contributes to blunted vasodilation induced by transient high pressure in human adipose microvessels.</a> Am J Physiol Heart Circ Physiol. 307 (1), H25-H32 (2014).</li><li>Farb, M. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cyclooxygenase+inhibition+improves+endothelial+vasomotor+dysfunction+of+visceral+adipose+arterioles+in+human+obesity.">Cyclooxygenase inhibition improves endothelial vasomotor dysfunction of visceral adipose arterioles in human obesity.</a> Obesity (Silver Spring). 22 (2), 349-355 (2014).</li><li>Park, S. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impact+of+age+on+the+vasodilatory+function+of+human+skeletal+muscle+feed+arteries.">Impact of age on the vasodilatory function of human skeletal muscle feed arteries.</a> Am J Physiol Heart Circ Physiol. 310 (2), H217-H225 (2016).</li><li>Ives, S. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+skeletal+muscle+feed+arteries+studied+in+vitro:+the+effect+of+temperature+on+alpha(1)-adrenergic+responsiveness.">Human skeletal muscle feed arteries studied in vitro: the effect of temperature on alpha(1)-adrenergic responsiveness.</a> Exp Physiol. 96 (9), 907-918 (2011).</li><li>Grizelj, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduced+flow-and+acetylcholine-induced+dilations+in+visceral+compared+to+subcutaneous+adipose+arterioles+in+human+morbid+obesity.">Reduced flow-and acetylcholine-induced dilations in visceral compared to subcutaneous adipose arterioles in human morbid obesity.</a> Microcirculation. 22 (1), 44-53 (2015).</li><li>Farb, M. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Arteriolar+function+in+visceral+adipose+tissue+is+impaired+in+human+obesity.">Arteriolar function in visceral adipose tissue is impaired in human obesity.</a> Arterioscler Thromb Vasc Biol. 32 (2), 467-473 (2012).</li><li>Tanner, M. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamin-Related+Protein+1+Mediates+Low+Glucose-Induced+Endothelial+Dysfunction+in+Human+Arterioles.">Dynamin-Related Protein 1 Mediates Low Glucose-Induced Endothelial Dysfunction in Human Arterioles.</a> Am J Physiol Heart Circ Physiol. , (2016).</li><li>Ives, S. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=alpha1-Adrenergic+responsiveness+in+human+skeletal+muscle+feed+arteries:+the+impact+of+reducing+extracellular+pH.">alpha1-Adrenergic responsiveness in human skeletal muscle feed arteries: the impact of reducing extracellular pH.</a> Exp Physiol. 98 (1), 256-267 (2013).</li><li>Dharmashankar, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nitric+oxide+synthase-dependent+vasodilation+of+human+subcutaneous+arterioles+correlates+with+noninvasive+measurements+of+endothelial+function.">Nitric oxide synthase-dependent vasodilation of human subcutaneous arterioles correlates with noninvasive measurements of endothelial function.</a> Am J Hypertens. 25 (5), 528-534 (2012).</li><li>Truran, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adipose+and+leptomeningeal+arteriole+endothelial+dysfunction+induced+by+beta-amyloid+peptide:+a+practical+human+model+to+study+Alzheimer's+disease+vasculopathy.">Adipose and leptomeningeal arteriole endothelial dysfunction induced by beta-amyloid peptide: a practical human model to study Alzheimer's disease vasculopathy.</a> J Neurosci Methods. 235, 123-129 (2014).</li><li>Karki, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Forkhead+box+O-1+modulation+improves+endothelial+insulin+resistance+in+human+obesity.">Forkhead box O-1 modulation improves endothelial insulin resistance in human obesity.</a> Arterioscler Thromb Vasc Biol. 35 (6), 1498-1506 (2015).</li><li>Shahid, M., Buys, E. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessing+murine+resistance+artery+function+using+pressure+myography.">Assessing murine resistance artery function using pressure myography.</a> J Vis Exp. (76), (2013).</li></ol>

Authors have no disclosures or conflicts of interest to report.

The dissection and isolation of adipose arterioles from surrounding tissues can be a time-consuming and labor-intensive process with careful attention to detail and technical protocol. The microdissection procedure requires meticulous skills and specialized dissection utensils to prevent potential damage to the smooth muscle or endothelial cell layers of the microvasculature. Even tiny accidental punctures in the arteriolar wall can prevent intraluminal pressurization and results in an unsuccessful experiment. Additional...

Videomicroscopy is a useful technique utilized to examine the vasomotor function of small arterioles removed from living human subjects ex vivo. Our laboratory has focused on dissecting out tiny microvessels from different adipose tissue compartments to characterize the effects of various adipose microenvironments on the microvasculature. A major advantage of this technique is that blood vessels removed from the human body remain functional and can be examined readily within minutes to hours following biopsy. Physiological conditions are mimicked and steady transmural pressure maintained in the intraluminal space via micro-glass cannulas which recapitulate many in vivo characteristics.1,2 Additionally, a reliable videomicroscopy set-up with automated edge detection software allows for both qualitative and quantitative assessment of endothelium-dependent and -independent vasodilator and vasoconstrictor capacity of isolated vessels in real-time, permitting rapid physiological assessment in response to physical and pharmacological stimuli.3 Other microvascular techniques are also available such as wire myography which tends to be less time consuming and measure tension responses to various agonists by a force transducer.
Our laboratory has applied videomicroscopy to examine the relationship between obesity and vascular dysfunction, focusing on the effects of different adipose tissue domains on the vasculature. Central adiposity with accumulation of intra-abdominal visceral fat has been most closely linked to adipocytokine production, metabolic dysfunction, and cardiometabolic risk. It has been postulated that adipose tissue dysfunction with over-production of pro-atherogenic cytokines and adipokine dysregulation are strongly implicated in these processes, but specific regulatory molecules and treatment targets remain largely undiscovered.4 Moreover, at the local adipose tissue level, capillary rarefaction and impaired perfusion have been linked to adipose tissue pseudohypoxia and metabolic dysregulation. The hypothesis that cardiovascular disease may be the consequence of adipose tissue dysfunction is evolving. Pro-atherogenic mediators released from fat, particularly in association with central/visceral adiposity, likely promote endothelial dysfunction and pathogenic vascular changes that can be manifest locally in the adipose vasculature and detected using the herein described methodology.5
The functional assessment of isolated adipose tissue arterioles is a useful approach to gain understanding of the pathophysiology and molecular mechanisms that contribute to vascular dysfunction in human obesity. To investigate mechanisms that contribute to fat depot-specific dysfunction, we have developed methods to examine endothelium-dependent and -independent vasodilatory responses of the microvasculature, and evaluate the expression of various regulatory candidates in paired visceral and subcutaneous (SC) fat tissue specimens obtained from obese subjects at the time of bariatric surgery.

<table border="0" cellpadding="0" cellspacing="0" width="769">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">Chemical Name</td>
			<td style="width:159px;"></td>
			<td style="width:132px;"></td>
			<td style="width:127px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">Acetylcholine</td>
			<td style="width:159px;">Sigma Aldrich</td>
			<td style="width:132px;">A6625</td>
			<td style="width:127px;"></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:352px;">Calcium chloride (CaCl2)</td>
			<td style="width:159px;">Sigma Aldrich</td>
			<td>223506</td>
			<td style="width:127px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">D-(+)-Glucose</td>
			<td style="width:159px;">Sigma Aldrich</td>
			<td style="width:132px;">G5767</td>
			<td style="width:127px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">Endothelin-1</td>
			<td style="width:159px;">Sigma Aldrich</td>
			<td style="width:132px;">E7764</td>
			<td style="width:127px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:352px;">Ethylene glycol-bis(2-aminoethylether)-N,N,N&#8217;,N&#8217;-tetra acetic acid (EGTA)</td>
			<td style="width:159px;">Sigma Aldrich</td>
			<td style="width:132px;">E3889</td>
			<td style="width:127px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">Ethylene diamine tetra acetic acid (EDTA)</td>
			<td style="width:159px;">Sigma Aldrich</td>
			<td style="width:132px;">E9884</td>
			<td style="width:127px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">HEPES</td>
			<td style="width:159px;">Sigma Aldrich</td>
			<td style="width:132px;">H3784</td>
			<td style="width:127px;"></td>
		</tr>
		<tr height="46">
			<td height="46" style="height:46px;width:352px;">Nw-nito-L-arginine methyl ester hydrochloride</td>
			<td style="width:159px;">Sigma Aldrich</td>
			<td style="width:132px;">N5751</td>
			<td style="width:127px;"></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:352px;">Magnesium sulfate (MgSO4)</td>
			<td style="width:159px;">Sigma Aldrich</td>
			<td style="width:132px;">M7506</td>
			<td style="width:127px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">Potassium chloride (KCL)</td>
			<td style="width:159px;">Sigma Aldrich</td>
			<td style="width:132px;">P3911</td>
			<td style="width:127px;"></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:352px;">Potassium phosphate (KH2PO4)</td>
			<td style="width:159px;">Sigma Aldrich</td>
			<td style="width:132px;">P5655</td>
			<td style="width:127px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">Papaverine</td>
			<td style="width:159px;">Sigma Aldrich</td>
			<td style="width:132px;">P3510</td>
			<td style="width:127px;"></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:352px;">Sodium bicarbonate (NaHCO3 )</td>
			<td style="width:159px;">Sigma Aldrich</td>
			<td style="width:132px;">S6014</td>
			<td style="width:127px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">Sodium chloride (NaCl)</td>
			<td style="width:159px;">Sigma Aldrich</td>
			<td style="width:132px;">S7653</td>
			<td style="width:127px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:352px;">Sodium phosphate monobasic monohydrate (NaH2Po4)</td>
			<td>Sigma Aldrich</td>
			<td>S9638</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Name</td>
			<td style="width:159px;">Company</td>
			<td style="width:132px;">Catalog Number</td>
			<td style="width:127px;">Comments</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Forceps</td>
			<td>Finescience tools</td>
			<td>15000-08</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Inverted microscope</td>
			<td>Zeiss Achromat</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Laboratory tubing</td>
			<td>Euro-Pharm</td>
			<td>250100306F999</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Needle/pippette puller</td>
			<td>David kopf instruments</td>
			<td>720</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Ophthalmic monofilament nylon suture</td>
			<td>Surgical specialties</td>
			<td>A7756N</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Scissors</td>
			<td>Finescience tools</td>
			<td>150000-08</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Vessel Chamber</td>
			<td>DMT</td>
			<td>VAS v.2.1</td>
			<td></td>
		</tr>
	</tbody>
</table>

assessment of human adipose tissue microvascular function using videomicroscopy

While obesity is closely linked to the development of metabolic and cardiovascular disease, little is known about mechanisms that govern these processes. It is hypothesized that pro-atherogenic mediators released from fat tissues particularly in association with central/visceral adiposity may promote pathogenic vascular changes locally and systemically, and the notion that cardiovascular disease may be the consequence of adipose tissue dysfunction continues to evolve. Here, we describe a unique method of videomicroscopy that involves analysis of vasodilator and vasoconstrictor responses of intact small human arterioles removed from the adipose depot of living human subjects. Videomicroscopy is used to examine functional properties of isolated microvessels in response to pharmacological or physiological stimuli using a pressured system that mimics in vivo conditions. The technique is a useful approach to gain understanding of the pathophysiology and molecular mechanisms that contribute to vascular dysfunction locally within the adipose tissue milieu. Moreover, abnormalities in the adipose tissue microvasculature have also been linked with systemic diseases. We applied this technique to examine depot-specific vascular responses in obese subjects. We assessed endothelium-dependent vasodilation to both increased flow and acetylcholine in adipose arterioles (50 - 350 &#181;m internal diameter, 2 - 3 mm in length) isolated from two different adipose depots during bariatric surgery from the same individual. We demonstrated that arterioles from visceral fat exhibit impaired endothelium-dependent vasodilation compared to vessels isolated from the subcutaneous depot. The findings suggest that the visceral microenvironment is associated with vascular endothelial dysfunction which may be relevant to clinical observation linking increased visceral adiposity to systemic disease mechanisms. The videomicroscopy technique can be used to examine vascular phenotypes from different fat depots as well as compare findings across individuals with different degrees of obesity and metabolic dysfunction. The method can also be used to examine vascular responses longitudinally in response to clinical interventions.

Our laboratory has used videomicroscopy to examine endothelium-dependent and -independent vasodilation, as well as vasocontractile function of adipose tissue arterioles isolated from subcutaneous and visceral fat of obese humans. The characteristic experimental set-up is displayed in Figure 1A. Adipose tissue arterioles are suspended between two glass capillary pipettes and secured in place with sutures within the organ chamber as shown in <strong class="xfig...

Watch this Scientific Journal Video about Assessment of Human Adipose Tissue Microvascular Function Using Videomicroscopy at JoVE.com

Assessment of Human Adipose Tissue Microvascular Function Using Videomicroscopy

Videomicroscopy systems are used to examine functional properties of isolated adipose tissue arterioles in response to physiological and pharmacological stimuli. This technique can be used to examine microvascular phenotypes in different adipose tissue domains in obese humans.

While obesity is closely linked to the development of metabolic and cardiovascular disease, little is known about mechanisms that govern these processes. ...

The overall goal of this videomicroscopy technique is to examine the functional properties of isolated microvessels in response to pharmacological and physiological stimuli, providing insight into the pathophysiology and molecular mechanisms that contribute to vascular dysfunction in humans. This method is useful for understanding the molecular mechanisms that contribute to dysfunction of the local microvasculature within fat, which has been linked to systemic diseases. The main advantages of this technique are that blood vessels remain functional after removal from the human body for a period of time and are easily examined for their physiologic properties.Clinical relevance of this experimental approach is that it allows us to identify pathways that are differentially altered in disease conditions and to potentially discover novel therapeutic targets. Under a tissue dissecting microscope, use microscissors and microforceps to carefully remove the surrounding fat and connective tissue from the small arterials within the adipose sample. It is essential to distinguish the arterials from the venules.Arterials are typically smaller in diameter, demonstrate a greater tone, and respond more robustly than do venules. When the arterial has been isolated, use nylon or silk sutures to tie off any branches. Next, use a 10 milliliter syringe to slowly fill the tubing with fresh Krebs solution.Then, attach rubber tubes to the pressure reservoirs and glass capillary pipettes within the chamber. Next, move the dissected arterial to the organ chamber and cannulate the vessel onto the glass capillary pipettes. Carefully secure both ends of the arterial on the pipettes with nylon sutures.Once the vessel is secure, slowly remove the Krebs buffer from the chamber and add two milliliters of fresh Krebs solution to the chamber. Next, attach the organ chamber to the stage of an inverted microscope equipped with a video camera. Turn on the edge detection software at a sampling rate of one kilohertz.Connect the remaining pressurized tubing to the second Krebs solution-filled pressure reservoir and then connect the pressure reservoirs to the pressure transducer. When all of the tubing has been connected, set the heating block to 37 degrees celsius. Next, use the pressure control unit to gradually increase the intraluminal pressure to five milliliters of mercury every five minutes to achieve the appropriate experimental pressure within the lumen of the isolated blood vessel.Allow the vessel to equilibrate for 20 to 30 minutes once the pressure reaches 60 milliliters of mercury and record the diameter of the adipose arterial at rest. At the end of the equilibration period, pre-constrict the blood vessel to approximately 55%of the resting baseline diameter by adding one microliter of endothelin 1 directly to the bath every five minutes until vessel diameter has been appropriately constricted. For flow-induced endothelial dependent vasodilation, induce continuous flow into the intraluminal space of the arterial in equal and opposite directions so that a pressure difference can be developed across the vessel without altering the mean intraluminal pressure of 60 millimeters mercury.After three to five minutes, measure the flow-mediated dilation. Increase each increment of pressure gradient by a 10 centimeter of water change every five to six minutes up to a maximum of 100 centimeters of water. After assessing the flow-mediated vessel dilation, return the pressure reservoirs to the same height to stop the induction of flow.Then immediately, but carefully replace the chamber solution with fresh Krebs solution without disturbing the suspended arterial and allow the vessel to begin to return to the baseline diameter for 20 to 30 minutes. Once the arterial has returned to the resting baseline diameter, a subtle choline-mediated endothelial dependent vasodilation can be assessed. This begins by pre-constricting the vessel to approximately 55%of its resting diameter with endothelin 1, as previously demonstrated.Once pre-constriction is achieved, add two microliters of increasing doses of acetylcholine directly to the bath. Record the change in arterial diameter five minutes following administration of each dose. Upon completion of the acetylcholine dose response, assess the endothelium independent vasodilation and vessel viability by the sequential administration of papaverine and endothelium independent vasodilator directly to the bath.Endothelium dependent vasodilation responses to increased flow and sheer stress or acetylcholine are significantly blunted in visceral versus subcutaneous adipose arterials in human obesity. Endothelium independent vasodilation in response to papaverine, however, is not differentially altered between the two dipose, suggesting that vascular dysfunction in visceral domains is largely a result of dysfunction at the level of the endothelium, at least in the early stages of the disease. Once mastered, this technique can be completed in three to five hours, if performed properly.While attempting this procedure, it's important to remember to take your time and be diligent, as even minor damages to the blood vessels may skew the results. Following this procedure, other methods like siRNA transfection of the blood vessels can be performed to answer additional questions about the impact of specific genes on vasomotor function in human disease. After it's development, this technique paved the way for researchers in the field of adipose tissue biology and microcirculation to explore the impact of the adipose tissue microenvironment on local vascular health in human obesity.After watching this video, you should have a good understanding of how to directly probe the pathophysiology of whole intact segments of human blood vessels, which are removed from living subjects, a process that cannot be replicated by non-invasive imaging.

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7.3K vistas.  Boston University School of Medicine. The overall goal of this videomicroscopy technique is to examine the functional properties of isolated microvessels in response to pharmacological and physiological stimuli, providing insight into the pathophysiology and molecular mechanisms that contribute to vascular dysfunction in humans. This method is useful for understanding the molecular mechanisms that contribute to dysfunction of the local microvasculature within fat, which has been linked to systemic diseases. The main advantages of...