Diffusion of oxygen from arterial to venous segments of renal capillaries

Abstract

Injections of three types of blood preparations were made into the renal arteries of dogs, namely, a) blood equilibrated with 95% O2, 5% CO2, b) arterial blood containing some methemoglobin-labeled erythrocytes and c) blood containing methemoglobinemic cells, but equilibrated with 95% O2, 5% CO2. The initial appearance time in the renal vein was 1.25 ± 0.97 second earlier for oxygen than for the methemoglobinemic red cells. When preparation c was introduced into the renal artery, a diphasic curve was consistently registered from the renal venous blood. The initial deflection was uniformly upright, indicating a preponderant effect due to increased oxygen saturation. This was followed by an inverted deflection, resulting from the predominant effect of methemoglobin. These findings are interpreted to indicate diffusion of some of the oxygen from arterial to venous limbs of capillary loops, probably the vasa recta located in the renal medulla.