Distribution of Renal Cortical Blood Flow during Hemorrhagic Hypotension in Conscious Dogs

The effect of hemorrhagic hypotension on distribution of renal cortical blood flow was investigated in 9 conscious dogs. 6 platinum electrodes were chronically implanted in inner and outer renal cortex and local cortical blood flow measured by hydrogen clearance. Urine was collected through a catheter implanted in the split bladder and total renal blood flow f RBF) determined by PAH clearance. In anesthetized dogs control blood flow averaged 3.72 ± 0.74 ml/min‐g in outer cortex and 3.60 ± 0.53 ml/rnin g in inner cortex. Local blood flow in conscious dogs fell to 30–60 % of control in the course of 11 days after implantation of the electrodes, though RBF was almost constant and filtering glomeruli were demonstrated in the small fibrotic zone (20–50 μ) close to the electrode tip. No change in local flow was found by induction of Nembutal anesthesia. Bleeding of conscious dogs 1–3 days after implantation, to mean arterial pressure 50 mm Hg, reduced local blood flow to 10–30 % of prebleeding control. The local blood flow in outer and inner cortex decreased near proportionately. Typically, flow at all electrode sites in outer and inner cortex showed a similar fall. A marked redistribution of cortical blood flow during hemorrhagic hypotension was never observed. Bilateral clamping of carotid arteries at normal and at low arterial pressures did not change outer or inner cortical blood flow.