Lithium stimulates thromboxane B2 formation in human platelets.

The aggregation of human platelets is enhanced after preincubations with lithium salts. Previously it was shown that lithium inhibits adenylate cyclase activity in human platelets. Enhancement of aggregation and inhibition of adenylate cyclase by lithium was not observed in rabbit platelets. In this paper it is shown that in human platelets lithium enhances considerably the synthesis of thromboxane B2, whereas the synthesis of PGE2 and PGF2 alpha was enhanced to a lesser extent. In rabbit platelets lithium had no effect on prostaglandin synthesis. It is concluded that lithium specifically stimulates the synthesis of thromboxanes in human platelets, probably due to the previously reported inhibition of adenylate cyclase activity, resulting in an increased aggregability.