Temperature-dependent coronary reactivity after perfusion with University of Wisconsin solution in the isolated rat heart.

The purpose of this study was to determine the effects of different temperatures of University of Wisconsin solution on the reactivity of the coronary vasculature in retrogradely perfused isolated rat hearts. Hearts were perfused for 30 min at 20 degrees C or single-flush perfused at 12 degrees C and 4 degrees C. To study both endothelium-dependent and direct effects on smooth muscle, vasodilation was induced with 5-hydroxytryptamine (5-HT) and nitroglycerin (GTN). The vasodilatory effects of 5-HT and GTN during basal conditions were completely lost and instead a vasoconstriction was observed after 30-min perfusion at 20 degrees C (5-HT: 23.7 +/- 5% before to -19.2 +/- 8% after perfusion; GTN: 33.7 +/- 5.5% before and -11.9 +/- 6% after perfusion). The same response was observed after single-flush perfusion at 12 degrees C (5-HT: 26.5 +/- 5% and -6.5 +/- 3% and GTN: 35.9 +/- 6% and -11.2 +/- 4% before and after perfusion, respectively). Single-flush perfusion at 4 degrees C did not alter the response to 5-HT and GTN (5-HT: 25.9 +/- 6% and 30.4 +/- 7% and GTN: 45 +/- 5% and 32.7 +/- 7% before and after perfusion, respectively). This study suggests that the coronary reactivity after perfusion with University of Wisconsin solution is dependent of the temperature of the solution and provides good preservation of the coronary vascular function at 4 degrees C, whereas temperatures above 12 degrees C might be detrimental.