Acute interaction of vasopressin and neurogenic mechanisms in DOC-salt hypertension.

We investigated the relative role of vasopressin and neurogenic factors in the control of vascular resistance in rats treated with desoxycorticosterone (DOC) and salt and in control rats. DOC-salt-treated rats had elevated hindquarter vascular resistance (P less than 0.05). Vasopressin and neurogenic tone contributed significantly (P less than 0.05) to increased resistance. Vasodilator responses to a specific vasopressin antagonist, I-deaminopenicillamine, 4-valine, 8-D-arginine vasopressin (dPVDAVP), and lumbar sympathectomy in separate DOC-salt groups accounted for 40 +/- 5 (SE) and 43 +/- 6%, respectively, of the total vasodilator capacity. In contrast, corresponding responses to dPVDAVP and lumbar sympathectomy in control rats were smaller (P less than 0.01), were significantly different (P less than 0.05), and accounted for 8 +/- 3 and 20 +/- 3%, respectively, of the total vasodilator capacity. Effects of dPVDAVP compared in innervated hindquarters of DOC-salt-treated and control rats were greater in DOC-salt-treated rats (P less than 0.001); in the denervated hindquarters the effects of dPVDAVP were similar in DOC-salt-treated and control rats. Therefore, effects of vasopressin on vascular resistance were augmented in DOC-salt-treated hypertensive rats; furthermore this augmented effect was dependent on an intact innervation.