Name: the mesenteric lymph duct cannulated rat model: application to the assessment of intestinal lymphatic drug transport
Uploaded: 2015-03-06T13:00:00
Description: Watch this Scientific Journal Video about The Mesenteric Lymph Duct Cannulated Rat Model: Application to the Assessment of Intestinal Lymphatic Drug Transport at JoVE.com

Funding from the Australian Research Council (ARC) and National Health and Medical Research Council (NHMRC) is gratefully acknowledged.

The studies described in this manuscript were approved by the local animal ethics committee and were conducted in accordance with the Australian and New Zealand Council for the Care of Animals in Research and Teaching guidelines. Prior to beginning any animal procedure, ensure that the appropriate permission is obtained through the local institution/organization. As with all animal surgeries, ensure that the surgery is performed by appropriately trained operators, under aseptic conditions and that anesthetics, analgesics...

The rat mesenteric lymph cannulation model enables direct quantification of the concentration and rate of transport of various cells and molecules (such as lipids and drugs) from the intestine into the lymph and the changes to these that occur in response to challenge of various substances (diet, antigen, drugs, formulations, etc.)10,27 and disease (cancer, viruses, colitis, insulin resistance, etc.)5-7. The components collected in lymph may also be further used in additional exper...

Lymph flows from the small intestine via a unidirectional process that originates at single lacteals that are contained within each small intestinal villi1. Lacteals are relatively permeable to fluid, macromolecules and cells and lymph formation thus commences with the entry of these factors into lacteals. The initial lymph in the lacteals subsequently flows from the intestine via a network of lymphatic microvessels, collecting (afferent) lymphatic vessels, a series of mesenteric lymph nodes and ultimately the post-nodal (efferent) lymph vessels. Within the nodes, lymph passes through a series of medullary sinuses where exchange occurs with node resident immune cells as well as material entering the node from the blood. All lymph flowing from the small intestine eventually converges into the efferent superior mesenteric lymph duct and subsequently the cisterna chyli. The cisterna chyli also collects lymph draining the caudal peripheral tissues, intestinal, hepatic and lumbar regions and joins the thoracic lymph duct together with lymph from the mediastinum and cranial parts of the body. The thoracic lymph duct empties lymph directly into the venous system at the junction of the left internal jugular and subclavian veins. The protocol described here, which enables the collection of lymph directly from the superior mesenteric lymph duct, thus facilitates the analysis of various factors transiting directly from the intestine to the systemic (general) circulation via the intestinal lymphatic system.
The major physiological functions assigned to the intestinal lymphatic system are to maintain fluid balance, to facilitate lipid and lipophilic molecule absorption, and to enable appropriate immune responses1. Tumor cells and viruses also propagate via the intestinal lymphatics2-4 and key changes occur within the lymphatics in several inflammatory and metabolic pathologies5-7. Cannulation of the mesenteric lymph duct to collect lymph within the mesentery enables an analysis of bulk fluid flow via the intestinal lymphatics as well as quantification of the concentration and transport rate of various cells and molecules. Changes to the concentration or transit of these factors in response to various challenges (e.g., diets, antigens, drugs) and in disease models (e.g., colitis, HIV, diabetes) can also be assessed. Whilst it is impossible to extensively describe each lymph component which may be analysed and compared here, mesenteric lymph simplistically consists of aqueous, lipid and cellular phases. Components of interest in the aqueous phase include peptides and proteins such as antigens or tolerogens8, immune messengers such as cytokines and mast cell mediators9, and metabolic mediators such as incretins10. The cellular fraction of the post-nodal mesenteric lymph consists almost entirely (over 99%) of lymphocytes11. Various immune cells (dendritic cells, mast cells, etc.) enter the pre-nodal mesenteric lymphatics but remain within the node12. If the cells within afferent lymph are of interest, it is possible to collect these cells via removal of the mesenteric lymph nodes several days before cannulation of the mesenteric lymph duct12. In this way the afferent and efferent lymph ducts are directly connected and the lymph cells in afferent lymph pass directly into the mesenteric lymph duct. The transit and phenotype of various immune cells passing through the intestinal lymphatics can thus be examined. Perhaps the most common reason cited for collecting mesenteric lymph to date, however, is to study the intestinal processing, absorption and transport of dietary lipids and lipophilic molecules10.
Following ingestion, dietary lipids are digested (for example, from triglyceride to fatty acids and monoglyceride, phospholipid to fatty acids and lysophospholipid, and cholesterol ester to fatty acid and cholesterol, etc.) and dispersed within the intestinal lumen into small micelle and vesicular structures via the addition of amphiphiles from bile (phospholipids, cholesterol and bile salts) and the action of pancreatic enzymes10,13. From here they are absorbed into enterocytes. A proportion of the absorbed components are re-esterified to form triglycerides, phospholipids and cholesterol esters within the absorptive cells (enterocytes). These re-esterified lipids are assembled from a combination of exogenously ingested lipid components and endogenous lipid components from the secreted bile, mucosal lipid pools or the intestinal blood supply13. From here the esterified lipids are either stored within enterocytes or assembled into intestinal lipoproteins (chylomicrons, very low density lipoproteins (VLDL)) together with various apoproteins and other lipophilic molecules (e.g., vitamins)10,13. After exiting enterocytes, lipoproteins are specifically transported from the intestine to the systemic circulation via the mesenteric lymphatic system as the intestinal lacteals are more permeable to their entry than the intestinal blood capillaries. A proportion of absorbed lipid components are also transported from the intestine to the systemic circulation via the blood capillaries and portal vein as single, non-lipoprotein associated, molecules14 . In general, however, the portal vein transport route is only a significant player in the absorption of short and medium chain length lipids.
The collection of mesenteric lymph thus enables the assessment of the transport of lipoproteins and associated components (lipids, lipophilic molecules, apo-proteins) from the intestine. The lipoproteins can be quantitated and characterized with the advantage that mesenteric lymph lipoproteins, in general, are in a nascent state since they have not been extensively modified by systemic enzymes such as lipoprotein lipase15. Whilst the mesenteric lymph cannulated rat model has perhaps historically been most extensively described for the analysis of lipid/lipoprotein transport from the intestine, an area of expanding interest is the role of lymphatics in the transport of lipophilic drugs, prodrugs and other xenobiotics13,16 which is the focus of the model described here. Lipophilic drugs (generally those with log P &#62; 5 and solubility in long-chain triglyceride &#62; 50 mg/g although exceptions are apparent)17,18, prodrugs19 and other xenobiotics13,16 can gain access to the intestinal lymphatics either passively or by actively integrating into intestinal lipoprotein transport pathways19.
The rat mesenteric lymph cannulation technique thus has many applications. Bollman et al. first described a technique to cannulate the mesenteric lymph duct in rats in 194820. Since then a number of variations on the model have been described. For example, collection can occur when the rat is anaesthetized with various anesthetics21,22, or in the conscious state whilst restrained15 or freely moving23,24. Rats can be administered different rehydration solutions and other substances such as lipids and drug formulations at different rates into the stomach, intestine or parenterally (typically 0 - 5 ml/hr)25. In some studies the thoracic lymph duct rather than mesenteric lymph duct is cannulated to estimate transport from the intestine via the lymphatics although this may overestimate transit from the small intestine, depending on the factor of interest, as the thoracic lymph duct also receives lymph from other regions22,26. Lymph cannulation models have also been described in several other species including mice15,27, mini-pigs12, sheep28,29, pigs30 and dogs31. However, the rat model is the most widely and consistently cited. Detailed protocols for cannulation of the mesenteric lymph duct followed by collection of lymph in conscious25 or anaesthetized22 rats and mice15,27 have been published previously and the interested reader is directed to these protocols. This protocol is the first to demonstrate the technique in a visualized format.
The lymph cannulated rat model has advantages over larger animal models in terms of expense, the ease of the surgery and ethical considerations. When compared to the mouse model, mesenteric lymph cannulation surgery is also easier in the rat although the mouse model enables more detailed studies in transgenic animals27. Nonetheless, there are some limitations of the rat model, particularly those associated with differences in physiology, that limit extrapolation to other pre-clinical and clinical situations. For example, in the rat bile flow is constant and independent of food intake whereas in higher species food or lipids stimulate bile flow32. This creates challenges to obtaining representative pre- and post-prandial environments in the rat that reflect what is seen in larger species and humans. For drug delivery studies, larger species may also be preferred when assessing lymphatic transport after the administration of realistic human dosage forms25. In a recent study, lipid transport rates in the mesenteric lymph were found to be comparable across species (mouse, rat, dog) after administration of an equivalent mass and type of lipid which provides some confidence in extrapolating lipid transport data across species27. However, the transport of a model lipophilic drug, halofantrine, ranked in the order of animal size (i.e., dog &#62; rat &#62; mouse). A scaling factor may thus be required to extrapolate lymphatic drug transport data from rat to other species.
A limitation of lymph cannulation models, in general, is that passive lymph collection directly from a lymphatic duct may modify lymph flow and transport since lymph vessels work against a pressure gradient that is altered once the vessel is cannulated33. The lymph cannulation model can also be difficult to establish in laboratories that are unfamiliar with the technique. Alternate models have thus been described. For instance, the transit of factors via the intestinal lymphatic system, such as lipoproteins and lipophilic molecules, has been indirectly studied via collection of blood. One such model involves comparing blood concentrations of lipids and/or drugs following oral administration in the presence and absence of inhibitors (e.g., colchicine, Pluronic L81, cycloheximide) of intestinal lipoprotein production that block lymphatic transport34. An advantage of models that quantify lymphatic transport indirectly via collection of blood samples is that it enables some evaluation of lymphatic transport in humans as invasive surgery is not required35. However, inhibitors of lymphatic transport are not specific and factors that are transported via the lymphatics are diluted and modified in the systemic circulation which complicates such assessments. In vitro alternatives have also been described. For example, caco-2 cell or isolated enterocyte cultures have been utilized to study in more detail the intestinal secretion of molecules that enter the lymphatics36-38. An advanced in vitro model that is more representative of the human intestinal microenvironment was also recently described39. In this model a lymphatic endothelial cell layer is co-cultured with Caco-2 cells which enables more detailed analysis of the transfer of substances from the intestine into the lymphatics. However, in vitro cell systems lack exchange flow and transfer ie interconnection with an intestinal lumen and underlying blood and lymphatic vascular supply. In an alternate approach, Kassis et al. established a dual-channel (high-speed bright-field video and fluorescence) in situ imaging system which enables quantitative comparisons between vessel contraction, lymph flow and fluorescent lipid concentrations in mesenteric lymphatic vessels33. An advantage of this model over the aforementioned in vitro systems is that it enables accurate tracking of the passage of immune cells through the lymphatics. Absolute measurements of mass lipid (or drug) transport are, however, not yet established using imaging methods. In vitro and in silico approaches to specifically predict the extent of lipophilic drug transport via the intestinal lymphatics have also been published40-42. For example, the ex vivo affinity of several compounds for plasma chylomicrons was found to correlate reasonably well with their lymphatic transport in vivo41. Subsequently, the same group established an in silico model to predict drug affinity for chylomicrons based on multiple physicochemical properties40. Holm et al. also established a relatively complex in silico model to outright predict lymphatic transport of lipophilic compounds on the basis of molecular descriptors42. These models may provide a useful approach to predict the extent of lymphatic transport of unknown drugs. Validation of the models with a wide range of drugs and across different labs will, however, be required to confirm their accuracy and reproducibility.
Cannulation of the mesenteric lymph duct thus remains the only means to directly examine the content of lymph draining the small intestine and the transit rate of the complex array of factors (cells, proteins, peptides, lipids, drugs) in lymph in an in vivo situation. Herein we describe a protocol for cannulation of the mesenteric lymph duct and carotid artery that enables the collection of mesenteric lymph and systemic blood from anaesthetized rats. Representative data demonstrate how the model can be used to examine lipid and drug transport from the intestine via the mesenteric lymphatic system. This is followed by a discussion of difficulties that can be encountered in establishing the model and a troubleshooting guide. Once established the model is a powerful tool to investigate intestinal lymphatic transport.

<table border="0" cellpadding="0" cellspacing="0" >
	<tbody>
		<tr >
			<td >Sterile saline</td>
			<td>Baxter healthcare</td>
			<td>AHB 1307</td>
			<td>Any brand can be used. Example here is Baxter 100 ml saline bags, box of 50</td>
		</tr>
		<tr >
			<td >70 % ethanol in water</td>
			<td>Any</td>
			<td></td>
			<td>Any brand can be used</td>
		</tr>
		<tr >
			<td >Chlorhexidine gluconate solution (Microshield 4)</td>
			<td>Livingstone International</td>
			<td>JJ60243L</td>
			<td>Any brand can be used. http://www.livingstone.com.au/?PG=search_result&#38;CAT=6&#38;search 
			=JJ60243L</td>
		</tr>
		<tr >
			<td >Betadine solution</td>
			<td>Livingstone International</td>
			<td>BU0510</td>
			<td>Any brand can be used. http://www.livingstone.com.au/?PG=search_result&#38;CAT=6&#38;search 
			=BU0510</td>
		</tr>
		<tr >
			<td >Ilium Ketamil (Ketamine 100 mg/ml)</td>
			<td >PROVET VICTORIA&#160;</td>
			<td >KETA I 1</td>
			<td>http://www.provet.com.au/</td>
		</tr>
		<tr >
			<td >Ilium Xylazil (Xylazine 100 mg/ml)</td>
			<td >PROVET VICTORIA&#160;</td>
			<td >TRO-3828</td>
			<td>http://www.provet.com.au/</td>
		</tr>
		<tr >
			<td >ACP 10 Injection (Acepromazine 10 mg/ml)</td>
			<td >PROVET VICTORIA&#160;</td>
			<td >VTG-DACP010020</td>
			<td>http://www.provet.com.au/</td>
		</tr>
		<tr >
			<td >Sodium pentobarbitone</td>
			<td>PROVET VICTORIA&#160;</td>
			<td>24529</td>
			<td>Any brand can be used. Example here is Lethabarb&#174; 325 mg/ml sodium pentobarbitone, Virbac Animal Health. http://www.provet.com.au</td>
		</tr>
		<tr >
			<td >Heparin (35000I.U. in 35 mL)</td>
			<td>Sigma Pharmaceuticals</td>
			<td>337220</td>
			<td>http://sigmaco.com.au/</td>
		</tr>
		<tr >
			<td >Ethylenediaminetetraacetic acid (EDTA) disodium salt dihydrate</td>
			<td >Sigma-Aldrich</td>
			<td >E1644</td>
			<td>Any brand can be used. Example here is disodium salt of EDTA from Sigma.&#160;</td>
		</tr>
		<tr >
			<td >Polyethylene (PE) cannula o.d. 0.96 mm x i.d. 0.58 mm</td>
			<td>Microtube extensions</td>
			<td>PE8050</td>
			<td>Any brand can be used. Example here is PE tubing 0.8x0.5 mm, 30 m</td>
		</tr>
		<tr >
			<td >Polyethylene (PE) cannula o.d. 0.8 mm x i.d. 0.5 mm</td>
			<td>Microtube extensions</td>
			<td>PE9658</td>
			<td>Any brand can be used. Example here is PE tubing 0.96x0.58 mm, 30 m</td>
		</tr>
		<tr >
			<td >Ruler</td>
			<td>Any</td>
			<td ></td>
			<td>Any brand can be used</td>
		</tr>
		<tr >
			<td >Markers</td>
			<td>Any</td>
			<td ></td>
			<td>Any brand can be used</td>
		</tr>
		<tr >
			<td >Cigarette lighter</td>
			<td>Any</td>
			<td ></td>
			<td>Any brand can be used</td>
		</tr>
		<tr >
			<td >Cyanoacrylate glue</td>
			<td>Any</td>
			<td ></td>
			<td>Any brand can be used</td>
		</tr>
		<tr >
			<td >23 gauge needles</td>
			<td>Livingstone International</td>
			<td>DN23GX0.75LV</td>
			<td>Any brand can be used. Example here is Livingstone Disposable Needle, Sterile, 23GX0.75inch, 100/BOX. http://www.livingstone.com.au/?PG=search_result&#38;CAT= 
			6&#38;search=DN23GX0.75LV</td>
		</tr>
		<tr >
			<td >25 gauge needles</td>
			<td>Livingstone International</td>
			<td>DN25GX1.0LV</td>
			<td>Any brand can be used. Example here is Livingstone Disposable Needle, Sterile, 25GX1.0inch, 100/BOX. http://www.livingstone.com.au/?PG=search_result&#38;CAT=6&#38;search= 
			DN25GX1.0LV</td>
		</tr>
		<tr >
			<td >1 ml syringe</td>
			<td>Livingstone International</td>
			<td>T3SS01TA</td>
			<td>Any brand can be used. Example here is Terumo syringe 1 ml Slip Tuberculin 100/Box. http://www.livingstone.com.au/?PG=search_result&#38;CAT=6&#38;search 
			=T3SS01TA</td>
		</tr>
		<tr >
			<td >10 ml syringe</td>
			<td>Livingstone International</td>
			<td>T3SS10SA</td>
			<td>Any brand can be used. Example here is Terumo syringe 10 ml Slip 100/Box. http://www.livingstone.com.au/?PG=search_result&#38;CAT=6&#38;search 
			=T3SS10SA</td>
		</tr>
		<tr >
			<td >Gauze swabs</td>
			<td>Livingstone International</td>
			<td>GSC075</td>
			<td>Any brand can be used and cut to required size. Example here is gauze swabs cotton filled 7.5x7.5 cm, 8 ply. http://www.livingstone.com.au/?PG=search_result&#38;CAT=6&#38;search 
			=GSC075</td>
		</tr>
		<tr >
			<td >Cotton buds</td>
			<td>Livingstone International</td>
			<td>CTAST075DP</td>
			<td>Any brand can be used. Example here is Livingstone cotton applicator plastic double tipped. 75MM. 100/PK. http://www.livingstone.com.au/?PG=search_result&#38;CAT=6&#38;search 
			=CTAST075DP</td>
		</tr>
		<tr >
			<td >Heating pad</td>
			<td>Ratek</td>
			<td>WT1</td>
			<td>Any brand that keeps temperature at 37C can be used. Example here is Ratek warming tray.</td>
		</tr>
		<tr >
			<td >Surgical light</td>
			<td>Harvard Apparatus</td>
			<td>72-0215 with 72-0267</td>
			<td>Any brand can be used. Example here is Harvard apparatus V-Lux 1000 Cold Light Source with Bifurcated Gooseneck Light Guide, Black, 4.7 mm fiber diameter (each arm). http://www.harvardapparatus.com/webapp/wcs/stores/servlet/product_11051_10001_50601_ 
			-1_HAI_ProductDetail and&#160; http://www.harvardapparatus.com/webapp/wcs/stores/servlet/product_11051_10001_35487_ 
			-1_HAI_ProductDetail___</td>
		</tr>
		<tr >
			<td >Surgical microscope</td>
			<td>Zeiss</td>
			<td>495005-0014-000</td>
			<td>Any brand can be used. Example here is Zeiss Stereomicroscope Stemi 2000-C with Stand S Double Spot and KL 300 LED. https://www.micro-shop.zeiss.com/?l=en&#38;p=us&#38;f=e&#38;i=10143</td>
		</tr>
		<tr >
			<td >Silk suture</td>
			<td>Livingstone International</td>
			<td>DTSK163019F4</td>
			<td>Any brand can be used. Example here is *&#160; 
			Email this item to my friend 
			3/8 Circle Reverse Cut Silk Suture 3/0 Thread 19mm. http://www.livingstone.com.au/?PG=search_result&#38;CAT=6&#38;search 
			=DTSK163019F4</td>
		</tr>
		<tr >
			<td >Scalpel blades</td>
			<td >Fine Science Tools (FST)</td>
			<td >10020-00</td>
			<td>Any brand can be used. Example here is FST Scalpel Blade #20. http://www.finescience.ca/Special-Pages/Products.aspx?ProductId=191</td>
		</tr>
		<tr >
			<td >Scalpel handle</td>
			<td >Fine Science Tools (FST)</td>
			<td>10004-13</td>
			<td>Any brand can be used. Example here is FST Scalpel Handle #4. http://www.finescience.ca/Special-Pages/Products.aspx?ProductId=298&#38;CategoryId=51</td>
		</tr>
		<tr >
			<td >1 x Small surgical scissors</td>
			<td >Fine Science Tools (FST)</td>
			<td>14060-09</td>
			<td>Any brand can be used. Example here is FST Fine Scissors, 9 cm with 21 mm cutting edge, sharp, straight. http://www.finescience.ca/Special-Pages/Products.aspx?ProductId=40&#38;CategoryId=17</td>
		</tr>
		<tr >
			<td >2 x Forceps with serrated curved tip</td>
			<td >Fine Science Tools (FST)</td>
			<td >11001-13</td>
			<td>Any brand can be used. Example here is FST 13 cm standard pattern forceps with curved 2.8x1.4 mm tip. http://www.finescience.ca/Special-Pages/Products.aspx?ProductId=405&#38;CategoryId=32</td>
		</tr>
		<tr >
			<td >1 x Iridectomy scissors</td>
			<td >Fine Science Tools (FST)</td>
			<td>15000-08</td>
			<td>Any brand can be used. Example here is FST Vannas Spring Scissors - 2.5mm Cutting Edge, Straight. http://www.finescience.ca/Special-Pages/Products.aspx?ProductId=17&#38;CategoryId=16&#160;</td>
		</tr>
		<tr >
			<td >1 x Forceps with straight serated tip</td>
			<td >Fine Science Tools (FST)</td>
			<td>11650-10</td>
			<td>Any brand can be used. Example here is FST Graefe 10 cm straight with serrated 1 x 0.99 mm tip. http://www.finescience.ca/Special-Pages/Products.aspx?ProductId=390&#38;CategoryId=32</td>
		</tr>
		<tr >
			<td >1 x Forceps with smooth sharp straight fine tip</td>
			<td >Fine Science Tools (FST)</td>
			<td>11251-10</td>
			<td>Any brand can be used. Example here is FST Dumont #5 forceps straight 11cm with 0.08 x 0.04mm tip. http://www.finescience.ca/Special-Pages/Products.aspx?ProductId=335&#38;CategoryId=29</td>
		</tr>
		<tr >
			<td >1 x Forceps with smooth fine curved forceps</td>
			<td >Fine Science Tools (FST)</td>
			<td>11063-07</td>
			<td>Any brand can be used. Example here is FST Delicate Forceps 9 cm with smooth 0.4 x 0.3mm tip. http://www.finescience.ca/Special-Pages/Products.aspx?ProductId=360</td>
		</tr>
		<tr >
			<td >2 x Hemostats</td>
			<td >Fine Science Tools (FST)</td>
			<td >13010-12</td>
			<td>Any brand can be used. Not all operators use the hemostats. Example here is FST 12 cm Micro-Mosquito Hemostats with 20 mm length x 1.3 mm width serrated, straight tip. http://www.finescience.ca/Special-Pages/Products.aspx?ProductId=377&#38;CategoryId=33</td>
		</tr>
		<tr >
			<td >1 x Suture needle holder</td>
			<td >Fine Science Tools (FST)</td>
			<td>12001-13</td>
			<td>Any brand can be used. Example here is FST 13cm Hasley Needle Holder with 16 mm length x 1.9 mm width tip. http://www.finescience.ca/Special-Pages/Products.aspx?ProductId=254&#38;CategoryId=70</td>
		</tr>
		<tr >
			<td >1 x Artery clamp</td>
			<td >Fine Science Tools (FST)</td>
			<td>18050-28</td>
			<td>Any brand can be used. Example here is FST Bulldog Serrefines straight, 28 mm long, 9x1.6 mm jaw dimension with medium clamp press. http://www.finescience.ca/Special-Pages/Products.aspx?ProductId=270&#38;CategoryId=82</td>
		</tr>
		<tr >
			<td >Oleic acid</td>
			<td >Sigma Aldrich</td>
			<td >O1008</td>
			<td>When required, any brand can be used. Example here is 99% pure oleic acid. http://www.sigmaaldrich.com/catalog/product/sial/o1008?lang=en&#38;region=AU</td>
		</tr>
		<tr >
			<td >14C-oleic acid</td>
			<td >Perkin&#160;</td>
			<td>NEC317050UC&#160;</td>
			<td>Any brand can be used. Example here is Oleic Acid, [1-14C]-, 50&#181;Ci (1.85MBq). http://www.perkinelmer.com/Catalog/Product/ID/NEC317050UC</td>
		</tr>
		<tr >
			<td >Sodium taurocholate</td>
			<td >Sigma Aldrich</td>
			<td >T4009</td>
			<td>Any brand can be used. Example here is taurocholic acid sodium salt hydrate &#8805;95% (TLC) . http://www.sigmaaldrich.com/catalog/product/sigma/t4009?lang=en&#38;region=AU</td>
		</tr>
		<tr >
			<td >Halofantrine</td>
			<td >Glaxo Smith Kline</td>
			<td ></td>
			<td>Halofantrine was kindly provided as a gift from Glaxo Smith Kline</td>
		</tr>
		<tr >
			<td >Sodium phosphate monobasic</td>
			<td >Sigma Aldrich</td>
			<td >71507</td>
			<td >Any brand can be used. Example here is sodium phosphate monobasic monohydrate, BioXtra, for molecular biology, &#62;99.5%. http://www.sigmaaldrich.com/catalog/product/sigma/71643?lang=en&#38;region=AU</td>
		</tr>
		<tr >
			<td >Sodium phosphate dibasic</td>
			<td >Sigma Aldrich</td>
			<td >71643</td>
			<td >Any brand can be used. Example here is sodium phosphate dibasic dihydrate, BioUltra, for molecular biology, &#62;99%. http://www.sigmaaldrich.com/catalog/product/sigma/71507?lang=en&#38;region=AU</td>
		</tr>
	</tbody>
</table>

the mesenteric lymph duct cannulated rat model: application to the assessment of intestinal lymphatic drug transport

The intestinal lymphatic system plays key roles in fluid transport, lipid absorption and immune function. Lymph flows directly from the small intestine via a series of lymphatic vessels and nodes that converge at the superior mesenteric lymph duct. Cannulation of the mesenteric lymph duct thus enables the collection of mesenteric lymph flowing from the intestine. Mesenteric lymph consists of a cellular fraction of immune cells (99% lymphocytes), aqueous fraction (fluid, peptides and proteins such as cytokines and gut hormones) and lipoprotein fraction (lipids, lipophilic molecules and apo-proteins). The mesenteric lymph duct cannulation model can therefore be used to measure the concentration and rate of transport of a range of factors from the intestine via the lymphatic system. Changes to these factors in response to different challenges (e.g., diets, antigens, drugs) and in disease (e.g., inflammatory bowel disease, HIV, diabetes) can also be determined. An area of expanding interest is the role of lymphatic transport in the absorption of orally administered lipophilic drugs and prodrugs that associate with intestinal lipid absorption pathways. Here we describe, in detail, a mesenteric lymph duct cannulated rat model which enables evaluation of the rate and extent of lipid and drug transport via the lymphatic system for several hours following intestinal delivery. The method is easily adaptable to the measurement of other parameters in lymph. We provide detailed descriptions of the difficulties that may be encountered when establishing this complex surgical method, as well as representative data from failed and successful experiments to provide instruction on how to confirm experimental success and interpret the data obtained.

The results of a representative experiment to quantitate the cumulative extent and rate of lipid and drug transport via the lymphatic system following intestinal delivery using the mesenteric lymph cannulation model are shown in Figure 4 and Figure 5. In this experiment, 200 &#181;g of the model lipophilic drug halofantrine was administered into the duodenum of rats over 2 hr in a formulation containing 40 mg oleic acid (including 2 - 5 &#181;Ci 14C-oleic acid) and 7.1 mg 2-mo...

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The Mesenteric Lymph Duct Cannulated Rat Model: Application to the Assessment of Intestinal Lymphatic Drug Transport

Here we describe a technique to cannulate the mesenteric lymph duct in rats which enables quantification of lipid and drug transport via the lymphatic system following intestinal delivery. The technique can be adapted to assess mesenteric lymph concentrations and/or transport of fluid, immune cells, peptides, proteins and lipophilic molecules.

The intestinal lymphatic system plays key roles in fluid transport, lipid absorption and immune function. Lymph flows directly from the small intestine ...

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