Glucose transport by proximal renal tubules.

TUNE, BRUCE M., AND MAURICE B. BURG. Glucose transport by proximal renal tubuler. Am. J. Physiol. 221(Z) : 580-585. 197 1 .-Glucose transport was studied in isolated, perfused rabbit proximal renal tubules. Glucose was actively transported out of the lumen of both the convoluted and straight portions. The rate of glucose transport was, however, much greater in the convoluted portion than in the straight portion. The concentration of glucose in proximal convoluted tubule cells was higher than in the surrounding fluids in perfused tubules, but not in nonperfused tubules. This localizes the site of active transport to the luminal cell membrane. The passive glucose permeability of the antiluminal cell surface was much greater than that of the luminal cell surface. There was a small but significant passive backflux of glucose through the tubule epithelium from bath to lumen. There was a transport maximum for glucose and this was independent of perfusion rate.