FUNCTIONAL IMPACT OF LYMPHANGIOGENESIS ON FLUID TRANSPORT AFTER LYMPH NODE EXCISION

Abstract

When a lymph node is excised, lymphangiogenesisoccurs to maintain flow in theaffected area. However, a complex network ofsmall vessels replaces the node and thesenewly formed vessels might increase resistanceto lymph transport. To test this in sheep, thepopliteal lymph node from one hind limb wasremoved surgically. The contralateral nodewas left intact. After 4 to 6 weeks (a periodthat allowed regenerated vessels to restoreflow), a prenodallymphatic vessel in each limbwas cannulated with a polyethylene catheterto permit saline infusion into the node orlymphatic regeneration site. Infusion pressureswere monitored from t-pieces inserted betweenthe infusion pump and the point of entry ofthe catheters in the prenodal ducts. Weobserved that the flow rate versus perfusionpressure relationships were significantlydifferent in the 2 experimental preparations(node intact limbs, n=13; node excised limbs,n=lO). In the limbs undergoing lymphangiogenesis,much higher infusion pressures wererequired to generate a given flow rate.Additionally, the regenerated lymphaticnetwork provided a significantly increasedresistance to flow. The data suggested thatlymphangiogenesis restored fluid continuity tosome extent in the area occupied originally bythe popliteal lymph node. However, thetransport properties exhibited by the newlyformed lymphatics were insufficient to restoreflow parameters to their original state.