Epinephrine overcomes the inhibitory effect of CP-CPK on FcγRIIA-mediated Ca⁺⁺ mobilization.

Platelets were loaded with 1-μmol/L Fura-2 as described in “Materials and methods” and stimulated by FcγRIIA cross-linking in the absence (A) or in the presence of A3P5PS (B) or CP-CPK (C). In (D), platelets were stimulated by FcγRIIA cross-linking in the absence (i) or in the presence of CP-CPK (ii) or CP-CPK and epinephrine (iii). In (iv), platelets were stimulated by 1-μmol/L epinephrine alone. The variations in fluorescence, reflecting changes in intracellular Ca⁺⁺ concentration, were monitored using a PTI Deltascan spectrofluorometer. Data are representative of 2 to 4 independent experiments.