Autoregulation of renal blood flow in spontaneously hypertensive rats.

Abstract

The relationship between renal blood flow (RBF) and arterial pressure was determined in 9 anesthetized, spontaneously hypertensive rats (SHR) of the Okamoto-Aoki strain and 7 Wistar-Kyoto rats (WKY). The rats had similar body weights and the average was 14-15 wk. Measured in vivo with a noncannulating electromagnetic flow transducer, RBF was stable in both groups in the pressure range of 165-105 mm Hg; renal vascular resistance (RVR) was directly related to pressure. Within this pressure range, RBF was .apprx. 6.7 ml/min in SHR and 7.3 ml/min in WKY. When perfusion pressure was reduced from 105-65 mm Hg, RBF decreased progressively, roughly in proportion to pressure. RBF and RVR did not differ significantly in SHR and WKY at each level of pressure. Similarity in the overall pressure-flow relationships was evident after RBF and RVR were normalized in each experiment to their respective values at the pressure of 115 mm Hg. Apparently SHR autoregulate RBF in vivo as efficiently as WKY and the sensitivity and reactivity of the renal vascular to acute changes in perfusion pressure are not modified appreciably in the SHR. The increased RVR in 15 wk old SHR can be explained as an appropriate autoregulatory response of the vasculature to the elevated arterial pressure.