EFFECTS OF UNIVERSITY-OF-WISCONSIN SOLUTION ON ENDOTHELIUM-DEPENDENT CORONARY-ARTERY RELAXATION IN THE RAT

University of Wisconsin (UW) solution has been reported to enhance myo cardial preservation in heart transplantation. To evaluate the effects of UW solution on coronary artery endothelial function, we designed e xperiments to compare UW solution with a standard crystalloid hyperkal emic cardioplegic solution (CHCS). Isolated rat hearts were studied in a modified Langendorff apparatus for coronary endothelial function. G roups 1 and 2 were perfused with 4 degrees C CHCS (24 mmol/L of KCl) a nd UW solution, respectively, for 10 minutes at a pressure of 80 cm H2 O, whereas group 3 underwent warm ischemia for 10 minutes. Groups 4 an d 5 were perfused with and stored for 4 hours in cold (4 degrees C) CH CS and UW solution, respectively. Group 6 underwent 4 hours of topical cooling (4 degrees C) without any cardioplegic perfusion. All groups had 6 hearts each. Endothelium-dependent relaxation and endothelium-in dependent relaxation of the coronary arteries were tested by infusing 5-hydroxytryptamine (5HT) (10(-6) mol/L) and sodium nitroprusside (10( -5) mol/L), respectively, before and after perfusion with and storage in one of the two cardioplegic solutions. The coronary vasodilatation induced by 5HT and sodium nitroprusside was not altered in hearts perf used with (group 1) or perfused with and stored in CHCS (group 4). Cor onary flow increase after 5HT infusion was significantly decreased in hearts perfused with (group 2) (before, 35% +/- 10%; after, 13% +/- 10 %; p < 0.01) or perfused with and stored in UW solution (group 5) (bef ore, 34% +/- 5%; after, -5% +/- 12%), indicating severe endothelial dy sfunction. In the latter group, coronary Bow increase with sodium nitr oprusside was also decreased, a finding suggesting smooth muscle damag e (before, 84% +/- 35%; after, 30% +/- 15%). Coronary arteries of hear ts having 4 hours of cold ischemia alone (group 6) had a significant d ecrease only in flow response to 5HT stimulation (before, 60% +/- 23%; after, 24% +/- 12%). These experiments suggest that perfusion with an d storage in UW solution does not preserve endothelium-dependent coron ary relaxation in the isolated rat heart.