ADP and adrenaline restored collagen-induced platelet aggregation.

(A) Responses of wild-type (WT) (upper panel) and Gαq-deficient platelets (lower panel) to 5 μg/mL collagen. Tritiated serotonin secretion is indicated in brackets. (B) ADP (10 μmol/L) restored aggregation in Gαq-deficient platelets and slightly enhanced secretion. (C) Adrenaline (10 μmol/L) similarly restored the collagen-induced aggregation of Gαq-deficient mouse platelets.