Renal glucose production and uptake in separate sites, and its significance

¹ Department of Pharmacology, University of Colorado School of Medicine, Denver, Colorado

Slices of rat kidney cortex, medulla, and papilla were incubated in serum under O₂-CO₂ mixtures, and their glucose exchanges measured. Cortical slices released more glucose than can be explained by glycogen or other tissue glucose forms, or slice swelling. Medullary and papillary slices, however, rapidly took up glucose, even when NaCl and/or urea were added to the serum to mimic probable in vivo conditions for these tissues. Renal glucose metabolism is discussed on the basis of these and other observations, leading to the following premises: a) glucose is formed in and released from proximal convolutions, while it is less certain that this occurs in distal convolutions; b) loops and collecting ducts, if not other nephron segments, may rely heavily on glucose for metabolic energy; and c) there are circumstantial relations between net renal glucose metabolism and diuresis.

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(With the Technical Assistance of Suzanne Dixon)