Abstract
Since it has been revealed that 20 to 30 per cent of maltose administered was excreted in urine, the role of the kidney in the metabolism of maltose was investigated.
When maltose was administered to nephrectomized rabbits, 14C-maltose disappeared from the blood stream very slowly and the increase in 14C-glucose was minimum. Maltase activities in the cortex of the kidney were ten times as high as in the medulla. In the isolated glomeruli, however, little maltase activities were observed. When maltose was injected to the rabbits pretreated with phloridzin, 14C-maltose decreased rapidly in blood and 14C-glucose did not increase. The difference between plasma maltose levels in the artery and vein across the kidney was increased after maltose was injected to the normal rabbits, whereas the plasma glucose concentrations in the renal vein exceeded those in the renal artery. In phloridzinized rabbits, the A-V difference of maltose was smaller as compared with normal rabbits and plasma glucose levels in the renal vein did not exceed those in the artery. The disappearance of 14C-maltose administered to the pancreatectomized rabbits was slightly delayed and urinary excretion of maltose and glucose increased. When the isolated kidney was perfused for 30 minutes with maltose solution, the levels of maltose and glucose in the renal vein rose and not only maltose but also glucose were excreted in urine.
These results suggest that the kidney plays an important role in the metabolism of maltose administered intravenously. The mechanism as to urinary excretion of glucose after maltose injection was discussed.
