Inhibition by forskolin of cytosolic calcium rise, shape change and aggregation in quin2‐loaded human platelets

Abstract

The adenylate cyclase stimulator forskolin was used to study the inhibitory effects of elevated cAMP on the activation of washed human platelets loaded with the fluorescent Ca2+ indicator quinl. In the presence of 10 μM isobutylmethylxanthine forskolin inhibited rises in [Ca2+]i evoked by thrombin and platelet-activating factor (PAF) due to both Ca2+ influx and release from internal stores with similar potency. Aggregation evoked by thrombin and PAF was suppressed whilst partial shape-change persisted, even in the absence of a measurable rise in [Ca2+]i. Forskolin did not affect the rise in [Ca2+i evoked by Ca2+ ionophore; aggregation was suppressed but shape-change persisted