Enhancement of endothelium-dependent contraction of the canine coronary artery by UW solution

University of Wisconsin (UW) solution has been used almost routinely in the preservation of the hepatic, pancreatic, renal, and cardiac allografts. However, its effect on vascular endothelium is unknown. Experiments were designed to evaluate its effect on canine coronary endothelium. Canine coronary arteries (n=8 in each group) were preserved in cold (4°C) UW solution (group 1) and physiological solution (group 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 (pO₂ 30±5 mmHg) caused endothelium-dependent contraction in the arteries of all 3 groups. However, vascular segments with endothelium of group 1 exhibited hypoxic contractions (107±26% of the initial tension contracted by prostaglandin F(2α) 2x10^-6 mol/L, P<0.05) that were significantly greater than those of the group 2 and group 3 segments with endothelium (25±5% and 20±4%). The hypoxic contraction in arteries of group 1 could be attenuated by N(G)-monomethyl-L- arginine (L-NMMA), the blocker of endothelial cell synthesis of the nitric oxide from L-arginine. The action of L-NMMA could be reversed by L-arginine but not D-arginine. Endothelium-dependent relaxation of coronary endothelium to acetylcholine and adenosine diphosphate and endothelium-independent relaxation and contraction of coronary smooth muscle were not altered by the UW solution. After preservation with the UW solution, endothelium-dependent contraction of the canine coronary arteries, occurs by L-arginine-dependent pathway, is enhanced. This augmentation by the UW solution would favor vasospasm after transplantation.