Energy requirement for sodium reabsorption in the in vivo rabbit kidney

Abstract

The relationship between reabsorbed sodium and O2 and consumption was studied in the in vivo rabbit kidney. Blood samples were taken from the femoral artery and directly from the left renal vein of anesthetized rabbits. Blood flow was measured directly from the renal vein. Urine was collected from the left ureter. Glomerular filtration rate was measured as inulin clearance; sodium reabsorption was obtained by subtracting the excreted sodium from the filtered sodium; oxygen consumption was calculated by multiplying the arterial-venous oxygen difference by the renal blood flow. The suprabasal aerobic energy consumption was found to be 1 M O2 consumed for every 30 Eq of Na+ reabsorbed. In addition, lactic acid production was measured to determine the amount of energy derived from anaerobic sources. There was no appreciable lactic acid production. These results are discussed in terms of efficiency of active Na+ transport across the renal tubular cell.