Endothelium, vasopressin receptors, and resistance to DOCA-salt hypertension.

Mesenteric artery rings from Wistar and Wistar-Furth rats subcutaneously treated with deoxycorticosterone acetate (DOCA) and 1% NaCl drinking water were used to measure endothelial modulation of contractile sensitivity and vasopressin receptor function and affinity. DOCA-salt hypertension reduced contractile sensitivity to arginine vasopressin (AVP) and did not affect contractile sensitivity to norepinephrine in arteries from Wistar rats. Endothelial removal caused a threefold increase in contractile sensitivity to AVP and norepinephrine in DOCA-salt hypertensive Wistar rats. In Wistar-Furth rats, DOCA-salt treatment did not affect contractile sensitivity to AVP, lysine vasopressin, oxytocin, and norepinephrine or the affinity of the vasopressin receptor for agonists or antagonists. Removal of endothelium did not affect vasopressin contractile sensitivity but caused a 15-fold increase in contractile sensitivity to norepinephrine in untreated or DOCA-salt-treated Wistar-Furth rats. These data show that reduced vasopressin receptor function and increased endothelial function that compensate for increased contractile sensitivity in arteries from DOCA-salt hypertensive Wistar rats are not the cause of resistance of DOCA-salt-treated Wistar-Furth rats to the development of enhanced contractile sensitivity and hypertension.