Thromboxane receptor stimulation inhibits adenylate cyclase and reduces cyclic AMP‐mediated inhibition of ADP‐evoked responses in fura‐2‐loaded human platelets

Abstract

Stimulation of human platelets with the thromboxane A₂ analogue, U46619, after treatment with prostaglandin E₁ or forskolin, reduced the inhibition of ADP-evoked Mn²⁺ influx and the release of Ca²⁺ from intracellular stores, U46619 decreased the elevated concentration of 3′, 5′-cyclic AMP in platelets that were pretreated with prostaglandin E₁. These results suggest that occupation of prostaglandin H₂/thromboxane A₂ receptors. like those for other agonists, inhibits adenylate cyclase activity, which can contribute to the promotion of platelet activation.