Rat liver lipids during ex vivo warm and cold ischemia and reperfusion

Rat livers were flushed and stored ex vivo in Krebs-Henseleit buffer at 37 degrees C for 3 hr or in University of Wisconsin solution at 2 degrees C for 48 hr. After this they were perfused with recirculated Krebs-Henseleit solution at 37 degrees C for 1 hr. Levels of phospholipids (PL), free fatty acids (FFA), and conjugated dienes were determined at various times during ischemia and after 1 hr of reperfusion. After 3 hr warm ischemia, total PL content decreased by about 30% primarily because of decreases in phosphatidylcholine and phosphatidylethanolamine. One hour of reperfusion normalized PL levels. Total PL content was unchanged up to 48 hr of cold ischemia because of offsetting alterations in levels of PL classes. FFA accumulation during warm ischemia was about half that during cold ischemia. Conjugated diene concentration increased fivefold during warm ischemia but was unchanged during cold ischemia. Low PL levels and FFA accumulation along with production of conjugated dienes suggest that lipid oxidation is a major mechanism of PL degradation during warm, but not cold, ischemia of the liver.