EFFECT OF TEMPERATURE IN LONG-TERM PRESERVATION OF VASCULAR ENDOTHELIAL AND SMOOTH-MUSCLE FUNCTION

Background. In clinical transplantation the donor organ is perfused wi th a cold preservation solution to obtain quick core cooling and a sui table environment for the tissue cells. Without good preservation of t he vasculature, progressive deterioration of the blood flow during rep erfusion may ultimately lead to the no-reflow phenomenon, even though the function of the other cells in the organ may be adequately preserv ed. The aim of this study was to find the optimal storage temperature for preservation of the vasculature. Methods. The infrarenal aorta of 126 Sprague-Dawley rats were studied in organ baths: as fresh controls , after 36 hours of storage at 0.5 degrees C, 4 degrees C, 8.5 degrees C, and 22 degrees C in University of Wisconsin solution, and after 36 -hour storage followed by transplantation and a lapse of 2 hours, 24 h ours, and 7 days. The thromboxane analogue U-46619 was used to test co ntractility. Acetylcholine was used to elicit endothelium-dependent re laxation (EDR), and papaverine to elicit endothelium-independent relax ation. Results. Storing the vessels at 0.5 degrees C proved best regar ding preservation of contractility, with a nonsignificant decrease, wh ereas storage at 4 degrees C and 8.5 degrees C resulted in a significa nt decrease after 36 hours. The contractility did not recover within 2 4 hours of in vivo reperfusion, but full recovery was seen after 7 day s. Regardless of the preservation temperature used, a significant impa irment in EDR was seen after 36 hours of storage. Two hours after tran splantation, vessels stored at 4 degrees C and 8.5 degrees C showed no significant impairment in EDR, whereas those stored at 0.5 degrees C demonstrated a significant loss of EDR. After 24 hours and after 7 day s, EDR was normal in all groups. Conclusions. Endothelium-dependent re laxing factor function is best preserved at 4 degrees C and 8.5 degree s C, whereas preservation of vascular smooth muscle function is best p reserved at 0.5 degrees C.