The Journal of clinical investigation
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Distribution of intrarenal blood flow was studied in 12 dogs anesthetized with Nembutal. Medullary blood flow was estimated by local clearance of hydrogen gas from the outer medulla measured polarographically with needleshaped platinum electrodes, and by local clearance of (85)Kr and mean transit time of (32)P-labeled erythrocytes measured with a small semiconductor detector placed in the outer medulla. Cortical blood flow was estimated from cortical red cell transit time and from total renal blood flow measured by electromagnetic flowmeter. ⋯ Reinfusion of blood after 2-3 hr of hypotension increased total renal blood flow to an average of 82% and outer medullary hydrogen clearance to an average of 92% of control values. All dogs survived the experiment without evidence of renal failure. It is concluded that hemorrhagic hypotension in dogs leads to a progressive and fairly uniform rise in renal vascular resistance, without any selective hemodynamic response in the juxtamedullary circulation.