Mechanism of lysophosphatidylcholine accumulation in the ischemic canine heart.
The metabolism of lysophosphatidylcholine (LPC) in non-ischemic and ischemic canine heart was investigated by in vitro enzyme analysis. Selected subcellular fractions were assayed for the LPC-producing enzyme phospholipase A and the LPC-eliminating enzymes LPC:acyl-CoA acyltransferase, LPC:LPC transacylase and lysophospholipase. The canine heart was found to contain all enzymes differing, however, in subcellular distribution and specific activity. Phospholipase A activity did not change significantly in any of the fractions prepared from the ischemic tissue of hearts rendered ischemic for 1, 3 or 5 hr when compared to non-ischemic tissue. Changes in the activity of the microsomal LPC:acyl-CoA acyltransferase over the course of 5 hr of ischemia were observed. Significant decreases in the activity of the cytosolic and microsomal lysophospholipases were detected especially after 3 and 5 hr of ischemia. Similarly, a decrease in the activity of the microsomal LPC:LPC transacylase was noted after 3 and 5 hr of ischemia. Our results suggest that impaired catabolism of LPC rather than an enhanced production of LPC is the principal mechanism for the increase in LPC levels in the ischemic canine heart.
Department of Pharmacology and Therapeutics, University of Manitoba, Faculty of Medicine, Winnipeg, Canada.
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D008243:1-Acylglycerophosphocholine O-Acyltransferase / Q000378:metabolism; D000217:Acyltransferases / Q000378:metabolism; D000818:Animals; D003327:Coronary Disease / Q000378:metabolism*; D004285:Dogs; D005260:Female; D066298:In Vitro Techniques; D008244:Lysophosphatidylcholines / Q000378:metabolism*; D008245:Lysophospholipase / Q000378:metabolism; D008297:Male; D009097:Multienzyme Complexes / Q000378:metabolism; D010741:Phospholipases A / Q000378:metabolism; D013347:Subcellular Fractions / Q000201:enzymology
D008244:Lysophosphatidylcholines; D009097:Multienzyme Complexes; D000217:Acyltransferases; D008243:1-Acylglycerophosphocholine O-Acyltransferase; D010741:Phospholipases A; D008245:Lysophospholipase; C021782:lysophospholipase-transacylase