Previous observations that platelet guanosine 3’. 5’-monophosphate (cyclic GMP) accumulation occurred during platelet aggregation and also in the presence of nitroprusside. which inhibits aggregation. prompted an evaluation of the effects of nitroprusside. nitric oxide. and related agents on human platelet aggregation. Adenosine diphosphate (ADP) was employed to induce irreversible aggregation ...