Basic aggregation properties of washed rat platelets: correlation between aggregation, phospholipid degradation, malondialdehyde, and thromboxane formation.

The basic characteristics of washed rat platelets in aggregation and biochemical responses to thrombin and collagen were investigated. Maximum aggregation response to thrombin and collagen was observed in the presence of 1-3 mM extracellular CA2+. Breakdown of endogenous phospholipids was followed by HPTLC. Phosphatidylinositol degraded most rapidly and greatly, followed by phosphatidylethanolamine, and phosphatidylcholine. Sphingomyelin did not change on stimulation. Formation of malondialdehyde was closely associated with thrombin- and collagen-induced aggregation within the range of the concentration employed. In addition, it was correlated with TXB2 formation and phosphatidylinositol degradation. These results indicated that, despite known species variation, thrombin-induced aggregation is mediated by TXA2 and malondialdehyde formation reflects both cyclo-oxygenase and thromboxane synthase activities, and phospholipid degradation in rat platelets as well as in human platelets.