Effect of Hemorrhagic Hypotension on the Distribution of Renal Cortical Blood Flow in Anesthetized Dogs

The distribution of renal cortical blood flow was studied in seven Nembutal anesthetized dogs in control periods, during hemorrhagic hypotension and after retransfusion. Local cortical blood flow was measured as hydrogen clearance recorded simultaneously from 3 to 6 platinum electrodes inserted into inner and outer half of the cortex. Total renal blood flow (RBF) was measured by electromagnetic flowmeter. In control periods flow averaged 3.47 ± 0.83 ml/min×g in outer cortex and 3.61 ± 0.86 ml/min × g in inner cortex. Bleeding to mean arterial pressure of 50 mm Hg in the course of 5–36 min in 5 expts. caused a proportional reduction of RBF and average flow in outer and inner cortex to 40–60 % of control, with further reduction to 10–30 % with maintenance of hypotension for 2 h. Bleeding to 70 mm Hg in 2 expts. gave princpially the same response. All electrodes showed a similar response and the percentual deviation between electrodes did not increase during hypotension. Thus no evidence was obtained for patchy or segmental ischemia or for regional redistribution of cortical blood flow. Retransfusion gave only incomplete restoration of flow.