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.
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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