In vivo EDRF activity influences platelet function

The administration of carbachol to rabbits to stimulate the release of endothelium derived relaxing factor (EDRF) results in inhibition of platelet aggregation and elevation of platelet cyclic GMP content. These effects are reversed by simultaneous administration of the EDRF inhibitors methylene blue or haemoglobin. The data provide the first direct biochemical evidence of in vivo EDRF activity.