<b>STIMULATION OF PHOSPHATIDYLCHOLINE METABOLISM IN RESERPINIZED RABBIT </b><b>PLATELETS </b>

Abstract

Phosphatidylcholine metabolism in blood platelets from the reserpinized rabbit was compared with that in the control platelets. A slight but significant increase in phosphatidylcholine content was observed in platelets from reserpinized rabbits. Incorporation of radioactivity into phosphatidylcholine from [3H]choline, [3H]metl1ionine or ["C]glycerol was significantly stimulated in the reserpinized cells. Thrombin induced a rapid and significant decrease in phosphatidylcholine content and an increase in lysophosphatidylcholine only in the reserpinized platelets, although thrombin rapidly decreased phosphatidylinositol content in both reserpinized and control platelets. These results suggest that the reserpinized platelets accumulate phosphatidylcholine intracellularly through the stimulation of the incorporation of choline moiety, the methylation of phosphatidylethanolamine, and the de nova synthesis from glycerol, and that phosphatidylcholine in the reserpinized platelets is rapidly degraded during thrombin-induced activation. It is possible that the enhancement of thrombin-induced release reaction of reserpinized platelets is associated with the active turnover of phosphatidylcholine.In response to thrombin, blood platelets from reserpine-treated rabbits aggregate and release their granular components more rapidly than control platelets, with production of a larger amount of malondialdehyde (l6-19). During