Some properties of the human platelet vasopressin receptor

Aggregation of human platelets by vasopressin is potently inhibited by 1-[beta mercapto-(beta, beta'-cyclopentamethylene propionic acid)]-L-arginine vasopressin, a selective vasopressor (V1) antagonist. 1-Desamino-8-D-arginine-vasopressin, a selective anti-diuretic (V2) agonist failed to induce aggregation and acted as a weak antagonist. Vasopressin analogues which lacked the N-terminal amino group or which contained an uncharged amino acid residue at position 8 acted as partial agonists for the human platelet. The response to such partial agonists could be enhanced by increasing the cytosolic Ca2+ concentration but not by altering the level of cyclic-3', 5'-AMP. These observations provide further evidence indicating that the platelet vasopressin receptor is of the V1 sub-type.