Positive interaction between agonists in the aggregation response of human blood platelets: interation between ADP, adrenaline and vasopressin

Human platelet vasopressin receptors

Specific saturable binding of 125I-arginine-vasopressin to human platelets is described. For ten normal volunteers the mean (+/- S.D.) KD is 5.6 nM (+/- 2.1) and the mean (+/- S.D.) Bmax is 115 fmoles/mg protein (+/- 30). Association studies indicate that equilibrium is reached after 90 minutes on ice. Pharmacological inhibition studies with analogues indicate that the platelet receptor is very similar to the kidney medulla receptor. The function of the receptor may involve serotonin release and platelet aggregation. Vasopressin binding to platelets should provide a readily means of assessing vasopressin receptor function in man.