Alterations of renal V1 and V2 receptors in spontaneously hypertensive rats and doca-salt hypertensive rats using computerized quantification for macro-autoradiogram

We previously examined the precise localization of vasopressin (VP) V1 and V2 receptors in the rat kidney using in vitro macro- and micro- autoradiography (ARG), and established the methodology of quantification for macro-ARG. In this study, to elucidate the role of VP in hypertension, we investigated the change within V1 and V2 receptors in the kidney of spontaneously hypertensive rats (SHR) and deoxycorticosterone acetate (DOCA)- salt hypertensive rats at different hypertensive stages. In SHR, although medullary V1 and V2 receptors decreased compared with age-matched Wistar- Kyoto (WKY) rats at the developmental hypertensive stage, these receptors increased once hypertension was established. Conversely, in DOCA-salt hypertensive rats, both renal V1 and V2 receptors decreased with elevated blood pressure. Therefore, expression of renal V1 and V2 receptors proved to be different between two models of hypertension, SHR and DOCA-salt hypertensive rats, when their blood pressure increases. In DOCA-salt hypertensive rats, renal V1 and V2 receptors may be down-regulated secondary to the high blood VP level. In SHR, the increase in renal V1 and V2 receptors may have a role in the development of high blood pressure in this strain of rats.