Critical importance of citrate--blood ratio in platelet aggregation studies.

ABSTRACT

The effects of citrate concentration on adenosinediphosphate-, epinephrine-, collagen-, and ristocetin-induced human platelet aggregation were investigated. Relatively small increments in citrate concentration markedly inhibited platelet aggregation by all three physiologic agents. The inhibitory effect was greatest on epinephrine-induced aggregation, and least on collagen-induced aggregation. Ristocetin-induced aggregation was not affected by excess citrate anticoagulation. These findings indicate the importance of controlling the citrateblood ratio in clinical platelet aggregation studies and in the assessment of antiplatelet drugs.