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

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Abstract
The relative role of vasopressin and neurogenic factors in the control of vascular resistance was investigated in rats treated with deoxycorticosterone (DOC) and salt and in control rats. DOC-salt-treated rats had elevated hindquarter vascular resistance (P < 0.05). Vasopressin and neurogenic tone contributed significantly (P < 0.05) to increased resistance. Vasodilator responses to a specific vasopressin antagonist, 1-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 < 0.01), were significantly different (P < 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 < 0.001); in the denervated hindquarters the effects of dPVDAVP were similar in DOC-salt-treated and control rats. Effects of vasopressin on vascular resistance were augmented in DOC-salt-treated hypertensive rats; furthermore this augmented effect was dependent on an intact innervation.