A study of regional distribution of renal blood flow using quantitative autoradiography.

Quantitative autoradiography utilizing [14C]iodoantipyrine was used to measure regional renal blood flow in anesthetized rats. This technique allowed blood flow in any region of the kidney to be measured with a resolution of 100 microns. There was no significant difference between flow to polar and middle regions of the renal cortex [875 +/- 57 vs. 926 +/- 71 (SE) ml.100 g-1 x mm-1]. Areas of high optical density in renal cortex corresponded to peritubular capillaries. Mean cortical blood flow was three times greater than mean medullary blood flow. Outer medullary blood flow was uniform but significantly higher than inner medullary blood flow (272 +/- 16 vs. 45 +/- 7 ml.100 g-1 x mm-1; P < 0.001).