Evidence for active phospholipase A in mouse plasma.
Mouse, rat and human plasma were exposed to minimum concentrations of disulphide or minimum pre-incubation at 55 degrees C in order to inhibit lecithin : cholesterol acyltransferase activity completely. The plasma samples were subsequently incubated at 37 degrees C and changes in individual phospholipid concentrations determined. Significant utilization of phosphatidylcholine and formation of lysophosphatidylcholine occurred only in disulphide-treated mouse plasma and this was accompanied by a decrease in total phospholipid concentration. When disulphide-treated mouse plasma was incubated with [U-14C]phosphatidylcholine radioactivity was additionally recovered in the lysophosphatidylcholine, non-esterified fatty acid and glycero-3-phosphocholine fractions; maximum conversion occurred at close to physiological pH. These observations suggest that phospholipase A and lysophosphatidylcholine hydrolase enzymes are active in mouse plasma but that phospholipase A is either absent or inactive in rat and human plasma.
D000818:Animals; D002784:Cholesterol / Q000097:blood; D004228:Dithionitrobenzoic Acid / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D008244:Lysophosphatidylcholines / Q000097:blood; D008297:Male; D051379:Mice; D007862:Phosphatidylcholine-Sterol O-Acyltransferase / Q000037:antagonists & inhibitors / Q000097:blood; D010713:Phosphatidylcholines / Q000097:blood; D010740:Phospholipases / Q000097:blood*; D010741:Phospholipases A / Q000097:blood*; D051381:Rats
D008244:Lysophosphatidylcholines; D010713:Phosphatidylcholines; D002784:Cholesterol; D004228:Dithionitrobenzoic Acid; D007862:Phosphatidylcholine-Sterol O-Acyltransferase; D010740:Phospholipases; D010741:Phospholipases A