Oxygen shunting in renal cortical and medullary capillaries

Abstract

The existence of shunting of oxygen from arterial to venous segments of the renal capillary bed was ascertained from densitometer tracings of renal venous blood after the injection into the renal artery of blood of high oxygen tension and containing optically labeled erythrocytes. The outer region of the renal cortex was functionally separated from the medulla plus inner cortex by means of regional hypothermia. There was observed no consistent exaggeration or attenuation of the diphasic character of the renal densitometer tracing characteristic of oxygen shunting by cooling either the superficial or deeper zones of the kidney. It is concluded that shunting of oxygen occurs in both the renal cortex and medulla, but the degree to which it occurs in each zone cannot be quantified from the present data.