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The Effect of Induced Lymph Flow on Protein Expression by Bovine Mesenteric Lymph Vessels

 Craig Quinlan*1, Randolph Stewart1, Emily Wilson2

 1Department of Veterinary Physiology & Pharmacology, College of Veterinary Medicine, Texas A&M University, College Station, TX, USA

2 Department of Medical Physiology, College of Veterinary Medicine, Texas A&M University, College Station, TX, USA


 Objective – We hypothesize that the expression of contractile proteins by lymphatic vessels will change following short term changes in lymph flow through the vessel.  We are investigating the truth of this hypothesis by observing variations in the expression of cofilin, profilin, and gelsolin by lymphatic smooth muscle.

Sample Population – Mesenteric lymph vessels were harvested from freshly slaughtered cattle.

Procedure – Bovine mesenteric lymphatic vessels in a tubular organ bath were perfused with a polyionic solution at 37°C and gassed with room air.  Using this in vitro cannulation method, we were able to control flow rate and transmural pressure.  The vessels were subjected to a short period (90 minutes) of induced lymph flow or no lymph flow, both at a constant transmural pressure.  After the 90-minute period, the vessels were snap frozen in liquid nitrogen and maintained at -80°C until Western blots were performed to quantify protein expression.  We are specifically looking for changes in the expression of the contractile proteins cofilin, profilin, and gelsolin.

Results – Preliminary experimentation which compared a control set of vessels that had not been exposed to the organ bath with a set of vessels that had been exposed to 90 minutes of constant wall tension with no lymph flow showed an overall average decrease in production of all three proteins.  Experimentation comparing vessels that experienced flow versus vessels that experienced no flow will offer a great deal of insight into the effects of lymph flow on lymphatic smooth muscle production of cofilin, profilin, and gelsolin.  Experiments in which shear stress and wall tension are central foci are to be conducted in the near future.

Conclusions and Clinical Relevance – Lymph vessels can indeed change protein expression in response to environmental changes in as short a period of time as 90 minutes.  This knowledge will eventually lead to new ways of looking edema formation and relief with the possibility of new methods of treatment and prevention of this complication.

Impact for Human Medicine – Interstitial edema formation, i.e. increased interstitial fluid volume, is a major contributor to organ failure in patients with cardiovascular disease.  The lymphatic system is the body’s main tool for alleviating interstitial edema.  Usually, lymphatic vessels actively propel interstitial fluid via cyclically contracting smooth muscle and unidirectional valves.  Interstitial fluid is transported through the lymphatic system and empties into the great veins of the neck (1, 2).  In response to high input (interstitial) pressure, the vessels act more like conduits by decreasing contractile activity which promotes passive lymph flow (3, 4).  Understanding the methods by which these changes take place could be very valuable in learning about the process of edema formation and relief.