Alterations in the metabolism of lipids in ischemia of the liver and kidney.

The metabolism of lipids in the ischemic liver has been examined in the attempt to define the cause of the previously described loss of phospholipid and to determine whether additional alterations occur that may be related to the disturbances in membrane function. With 3 hr of ischemia, 30% of the cellular phospholipid was lost when measured either as phosphate in a lipid extract of the whole liver or as fatty acyl esters after separation by thin-layer chromatography of the major lipid classes in the same extracts. All phospholipid species were equally affected, and there was no accumulation of lysophospholipids. The loss of phospholipid acyl chains was not accompanied by an increased number of acyl esters as mono-, di-, or triglycerides. There was no increase in the size of the free fatty acid pool, and the content of long chain acyl CoA esters decreased by 50%. The acyl chain composition of the free fatty acid and neutral lipid pools changed, however, to resemble more closely that of the phospholipids. There was no change in the fatty acid composition of the phospholipids. The incorporation of intraportally injected [3H]arachidonic acid into total phospholipids was decreased upon reperfusion of liver that had been ischemic for only 20 min. These data are consistent with a loss of fatty acyl chains from the phospholipids into the free fatty acid pool. A few of these chains are incorporated into neutral lipids, but most are lost from the liver.(ABSTRACT TRUNCATED AT 250 WORDS)