The relationship between glomerular filtration rate and sodium reabsorption by the proximal tubule of the rat nephron

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Abstract

We have tested two of the hypotheses proposed to explain the adjustment in sodium reabsorption in the proximal tubule that follows a change in the rate of glomerular filtration (glomerulotubular balance). Using the recollection micropuncture technique, we were able to measure the immediate and late changes in reabsorptive rate after an acute alteration in filtration rate produced by aortic constriction and release of constriction. It was found that fractional reabsorption, as measured by the inulin tubule fluid to plasma (TF/P) ratio, increased after aortic constriction and decreased after release, but that in most instances, absolute reabsorptive rate changed in parallel to glomerular filtration rate. The change was similar whether the collections were made less than 1 or more than 5 min after the change in blood pressure. The rapid time course of this adjustment in reabsorptive rate is viewed as evidence against an intrarenal humoral feedback mechanism.

Authors

Barry M. Brenner, Cleaves M. Bennett, Robert W. Berliner