Vasopressin V1a and V2 receptor mRNA in deoxycorticosterone acetate-salt hypertension in the rat

Abstract

1. Vasopressin V1a and V2 receptors are differentially regulated in deoxycorticosterone acetate-salt hypertension. This paper investigated whether the changes were due to transcription changes in receptor mRNA assessed by in situ hybridization histochemistry (liver V1a receptor) and by reverse transcription-polymerase chain reaction (kidney V1a and V2 receptor). 2. Systolic blood pressure and plasma vasopressin levels were significantly elevated in deoxycorticosterone acetate-salt rats (n = 24) compared with water-control (n = 28) and salt-control rats (n = 28) (P < 0.001). Plasma sodium was elevated in deoxycorticosterone acetate-salt rats compared with both control groups (P < 0.01) and plasma osmolality was elevated in deoxycorticosterone acetate-salt rats compared with water-control rats (P < 0.05). 3. Binding kinetic studies demonstrated downregulation of liver V1a and kidney V2 receptors in deoxycorticosterone acetate-salt rats compared with water-control and salt-control rats (P < 0.05). This was not associated with any change in liver V1a receptor mRNA (P = 0.95), or in kidney V1a (P = 0.79) or V2 receptor mRNA (P = 0.96). 4. In deoxycorticosterone acetate-salt hypertension, downregulation of liver V1a and kidney V2 receptors occurs in the setting of stable vasopressin gene transcription. These results suggest that changes in receptor processing may be responsible for the differential regulation of vasopressin receptors that occurs in deoxycorticosterone acetate-salt hypertension.