ENHANCEMENT OF ENDOTHELIUM-DEPENDENT CONTRACTION OF THE CANINE CORONARY-ARTERY BY UW SOLUTION

University of Wisconsin (UW) solution has been used almost routinely i n the preservation of the hepatic, pancreatic, renal, and cardiac allo grafts. However, its effect on vascular endothelium is unknown. Experi ments were designed to evaluate its effect on canine coronary endothel ium. Canine coronary arteries (n=8 in each group) were preserved in co ld (4 degrees C) UW solution (group 1) and physiological solution (gro up 2) for 6 hr immediately after harvesting. Segments of preserved and control (group 3) coronary arteries with or without endothelium were then suspended in organ chambers to measure isometric force. Perfusate hypoxia (pO(2) 30+/-5 mmHg) caused endothelium-dependent contraction in the arteries of all 3 groups. However, vascular segments with endot helium of group 1 exhibited hypoxic contractions (107+/-26% of the ini tial tension contracted by prostaglandin F-2 alpha 2x10(-6) mol/L, P<0 .05) that were significantly greater than those of the group 2 and gro up 3 segments with endothelium (25+/-5% and 20+/-4%). The hypoxic cont raction in arteries of group 1 could be attenuated by N-G-monomethyl-L -arginine (L-NMMA), the blocker of endothelial cell synthesis of the n itric oxide from L-arginine. The action of L-NMMA could be reversed by L-arginine but nest D-arginine. Endothelium-dependent relaxation of c oronary endothelium to acetylcholine and adenosine diphosphate and end othelium-independent relaxation and contraction of coronary smooth mus cle were not altered by the UW solution. After preservation with the U W solution, endothelium-dependent contraction of the canine coronary a rteries, occurs by L-arginine-dependent pathway, is enhanced. This aug mentation by the UW solution would favor vasospasm after transplantati on.