AVP and Hypertension: Furthermore, while the role of ADH in the development of hypertension via V1a receptor stimulation was shown by the hypotensive effect of OPC-21268, a non-peptide ADH V1a antagonist, in young SHR, with a more pronounced effect in male than in female rats and the interesting observation of a persistence of low BP levels after the drug withdrawal (54), other reports were unable to demonstrate such a hypotensive effect by the chronic treatment with specific V1 receptor antagonism (55).