Influence of variations in blood flow on renal A-V oxygen difference and renal oxygen consumption in heart failure. A clinical study

Abstract

In the present study, renal A-V oxygen difference and renal blood flow were measured in 18 patients with mitral valvular disease. The renal sodium reabsorption and oxygen consumption have also been measured. The renal A-V oxygen difference was small and remained within the normal range despite large reductions in renal blood flow. Only when flow fell to between 400 and 500 ml. per minute there was a rise in A-V oxygen difference. The renal oxygen consumption was in general reduced compared with normal subjects, but tended to increase in those patients who also had the greatest values for A-V oxygen difference. The renal oxygen consumption was found to vary independently of the sodium reabsorption. Our results indicate a shift to a more aerobic renal metabolism in advanced heart failure when renal blood flow is drastically reduced. It is possible that the variations in oxygen demand may reflect changes in substrate requirements for transport of sodium in different circulatory situations. Redistribution of flow within the kidney at low renal blood flow as well as the possibility of passive transport of sodium in the proximal tubules might also account for the changing relationship between A-V difference and renal blood flow.