Changes in vascular vasopressin receptors and responsiveness in DOCA/NaCl-treated rats

This study investigated the effects of treatment with desoxycorticosterone acetate and salt (DOCA/NaCl) on blood pressure, aortic vascular vasopressin receptors and in vitro vascular responsiveness in male rats. Four groups of animals were utilized in the study: a control group on normal tap water, a control group drinking a 1% NaCl solution; a DOCA/NaCl-treated group (1% NaCl in the drinking water); and a uninephrectomized (1K) DOCA/NaCl-treated group. DOCA/NaCl treatment for 4 weeks resulted in a significant elevation in blood pressure which was more pronounced in the uninephrectomized animal. The concentration of specific binding sites for vasopressin on the aorta were reduced in both the DOCA/NaCl-treated groups. However, the vascular responsiveness of the aorta to vasopressin was significantly reduced only in the hypertensive, uninephrectomized-DOCA/NaCl-(1K DOCA/NaCl) treated rat. Both the maximal contraction and the sensitivity was reduced in the 1K DOCA/NaCl group. The results of this study would suggest that the vascular alterations to vasopressin are probably post receptor mediated and result from the DOCA/NaCl-induced hypertension.