Hemodynamics of early experimental renal hypertension in dogs. Normal limb blood flow, elevated limb vascular resistance, and decreased venous compliance.

Abstract

To investigate the hemodynamics of early experimental renal hypertension, skin and muscle blood flows and intravascular pressures were measured in the isolated, innervated, naturally perfused forelimbs of 44 male mongrel dogs under pentobarbital (35 mg/kg) anesthesia. In addition, venous pressure-volume relationships were studied in temporarily isolated segments of femoral and jugular veins. In 10 dogs (group H-1) one kidney was wrapped in silk 8 days before study; in 12 (H-2) one kidney was wrapped 4 weeks, and a contralateral nephrectomy was done 2 weeks, before study; 22 were prepared as appropriate normotensive controls. A significant rise in mean arterial pressure occurred in groups H-1 and H-2. Compared to corresponding control groups, (1) muscle and skin blood flows in both hypertensive groups were unchanged ( P >0.1); (2) muscle and skin resistances/100 g limb weight were increased in group H-2 ( P <0.05); and (3) femoral venous pressure-volume curves were shifted toward the pressure axis ( P <0.02). These data suggest that in the early stages of experimental renal hypertension in dogs: (1) blood flow in skin and skeletal muscle is not increased; (2) arteriolar resistance is elevated in skin and skeletal muscle; and (3) reduced venous compliance may be present.