SummaryThe distribution of blood flow between four zones of the canine renal cortex was measured by the tracer-labeled microsphere technique. The effect of ureteral occlusion on cortex zone flow distribution was studied during saline diuresis, mannitol diuresis, and ethacrynic acid diuresis. Renal venous constriction was performed in oliguric animals. The venous pressure was elevated to an average of 62.2 mm Hg, the highest level at which renal blood flow remained constant. Both ureteral occlusion and renal venous constriction resulted in a redistribution of flow from the most superficial cortex to deeper cortex zones. We infer that the redistribution reflects the renal circulatory response to elevated renal interstitial pressure since it was produced by both renal venous constriction and ureteral occlusion and was independent of the type of accompanying diuresis. This redistribution was found to be indistinguishable from that caused by reduction in renal arterial pressure. This suggests that a common mec...