An energy‐dependent, sodium‐independent component of active p‐aminohippurate transport in rabbit renal cortex.

Abstract

SUMMARY1. The relation between the coupling of metabolic energy to renal p-aminohippurate (PAH) accumulation and Na+-K+ transport was studied in rabbit cortical slices.2. Cyanide (CN-), 2,4-dinitrophenol (DNP) and fluoride (F-) at low-medium concentrations, giving rise to a slight decline of tissue ATP concentration, caused a reduction of PAH accumulation without significantly affecting intracellular Na+ and K+ concentrations. However, higher levels of the metabolic inhibitors also resulted in considerable inhibition of active Na+-K+ transport.3. The rate of carrier-mediated PAH uptake was slow under anaerobic conditions, relative to that measured under aerobic conditions in Na+-depleted slices. In the latter case the maximal accumulation achieved was only 1-55 + 0-16.4. The uptake rate of PAH under anaerobic conditions was not inhibited by the absence of Na+ or addition of metabolic inhibitors in the concentrations used under aerobic conditions. 5. It is concluded that although Na+ is required for the attainment of high accumulation ratios of PAH, oxidative metabolism stimulates PAH flux by a Na+-independent mechanism.

Involvement of Na+‐K+‐ATPase in p‐aminohippurate transport by rabbit kidney tissue.

“…Despite the disputable role of Na+ in PAH accumulation under anaerobic conditions, the presence of this cation is required to obtain appreciable accumulation of PAH under aerobic conditions (Gerencser et al 1973;Gerencser & Hong, 1975;Podevin & Boumendil-Podevin, 1977;Maxild et al 1981). The present data strongly support the view that the major part of the intracellular accumulation of PAH by rabbit kidney slices under aerobic conditions is dependent on the function of the Na+-K+-ATPase in the preparation.…”

“…At the end of the incubation PAH, and inulin or ouabain when present, were -extracted from the slices with 5 % (w/v) trichloroacetic acid. Procedures for determination of radioactively labelled substances, PAH, Na+, K+ and ATP were as previously described (Maxild et al 1981). Uptake of PAH by the kidney slices was expressed as the ratio of tubular concentration and medium concentration (T/MpAH), after correction for inulin space, also as previously described (Maxild et al 1981).…”

Effects of cysteine derivatives of styrene on the transport ofp-aminohippurate ion in renal plasma membrane vesicles

“…It is also generally recognized that there is a functional link between the PAH transport and Na+-K+-ATPase activity (Spencer et al 1979;Maxild et al 1981;Sheikh et al 1981). The probenecid-sensitive active tubular secretion of organic anions such as PAH is also known to be sodium dependent (Chung et al 1970;Gerencser et al 1973;Gerencser, Hong 1975) and is inhibited when the Na+-K +-ATPase activity is depressed (Spencer et al 1979).…”

The contribution of marine biology to biomedical research: Past, present, future

“…Such a mechanism has proved to be operating also for example in the excretion of uric acid in crustaceans (A. Nies et al, unpubl, obs. ) as well as in mammals (Maxild et al. 1981).…”