Uptake of lactate and pyruvate by intact kidney of the dog

Abstract

In dogs anesthetized with pentobarbital, mean renal blood flow was 312 ml/min/100 g kidney wt., and mean renal O₂ consumption was 6.46 ml/min/100 g. Under control conditions mean net uptake of lactate was 20.7 µM/min/100 g. The precise metabolic fate of lactate could not be ascertained from these studies. If it were completely oxidized, it would account for 21.6% of the total O₂ consumption. When blood lactate levels were raised by infusion of L(+)lactate, there was a progressive increase in rate of uptake. Under control conditions, the net handling of pyruvate delivered to the kidney was negligible. When blood levels were elevated by pyruvate infusions, there was significant net uptake; when pyruvate levels increased as the result of lactate infusions, there was no augmentation of net uptake. Similarly, elevated levels of lactate occurring during pyruvate infusions did not elicit significant acceleration of lactate uptake. When renal blood flow was acutely reduced, renal extraction of oxygen, lactate, and pyruvate remained remarkably constant. Thus, a decrease in net uptake of oxygen and lactate was proportional to the rate of blood flow, and pyruvate uptake was negligible over the entire range of blood flows.