Effect of changes in renal perfusion pressure on the suppression of proximal tubular sodium reabsorption due to saline loading

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Abstract

Rapid intravenous infusion of saline is known to suppress reabsorption of sodium and water in the proximal tubule. It has previously been shown that this suppression is accompanied by two changes which in combination might account for the over-all decrease in reabsorption: a reduction in the intrinsic reabsorptive capacity of the tubular epithelium (C/πr2) and a reduction in the ratio between tubular volume and GFR (πr2d/Vo). The present micropuncture experiments were carried out in order to study the possible role of altered peritubular physical forces (hydrostatic and colloid oncotic pressure) in mediating these two changes. Proximal tubular reabsorptive capacity, transit time, fractional reabsorption of sodium and water, πr2d/Vo, and intratubular hydrostatic pressure were measured in saline-loaded rats during acute changes in renal perfusion pressure induced by intermittent constriction of the abdominal aorta.

Authors

Norman Bank, Karl M. Koch, Hagop S. Aynedjian, Marc Aras