Calmodulin Antagonist W-7 Inhibits Aggregation of Human Platelets Induced by Platelet Activating Factor

Abstract

Experiments were done to test the hypothesis that aggregation of human platelets induced by platelet activating factor (PAF) may be mediated by calmodulin-dependent processes. W-7 [N-(6-aminohexyl)-5-chloro-l-naphthalene sulfonamide], a potent calmodulin antagonist, caused dose-dependent inhibition of PAF induced aggregation of human platelets in vitro. The ED₅o for W-7 was 51.5 ± 9.5 μM (mean ± SEM). This concentration is known to be platelet calmodul in-specific. These data are consistent with the hypothesis.