Renal handling of glucose in dogs

Abstract

Evidence has been obtained that glucose is transported across renal tubule cells with the 6-carbon chain intact and that glucose does not contribute significantly to renal carbon dioxide production. Injection is made rapidly into a renal artery of solutions containing T-1824 (assumed not to leave the circulation), creatinine and glucose appropriately labeled with C14. Relative to T-1824, creatinine recovery in renal vein blood averaged 74%; glucose recovery averaged 98%. Differences were apparent in the time-concentration curves of glucose and of creatinine; these disappeared after phlorizin and are considered to represent reabsorbed glucose. That little or none of the injected glucose was converted to nonvolatile carbon compounds was shown by paper chromatograms and radioautographs. That the carbon chain was not broken down and resynthesized was shown by the nonrandomization of C14 injected as glucose-1-C14 and as glucose-6-C14 in glucose recovered from renal venous blood. Analysis for C14O2 of renal venous blood samples, collected anaerobically, showed that less than 0.2% of the injected glucose was converted to carbon dioxide. Urinary excretion patterns of glucose and creatinine were symmetrical, except for a slight delay in the appearance of glucose, during glucosuria from glucose loading and after phlorizin administration. Glucose does not appear to enter the tubule cells from the lumen and subsequently to return to the urine. The transit time of reabsorbed glucose across the tubule cells averages 10 seconds.