The role of cortical na,k-atpase in distal nephron potassium secretion by the immature canine kidney

ABSTRACT ABSTRACT: Amiloride-sensitive potassium secretion in response to acute potassium loading is lower in the newborn than in the adult. Potassium secretion is a function of late distal

tubule and cortical collecting tubule Na,K-ATPase activity. Na,K-ATPase activity _in vivo_ is determined by enzyme abundance and catalytic turnover. Chronic potassium supplementation

increases potassium secretory capacity in the adult by increasing enzyme abundance in the late distal and cortical collecting tubules. We hypothesized that the lower potassium secretory

capacity of the newborn was the result of lower late distal and cortical collecting tubule Na,K-ATPase activity and could be similarly enhanced. To test this hypothesis, newborn dogs were

supplemented with 6 mmol KCl·d−1·kg−1 for 1 wk; age-matched litter mate controls were not (_n_ = 8 pairs). Potassium supplementation resulted in a mean increase in Vmax Na,K-ATPase activity

_in vitro_ (proportional to pump abundance) of 70 ± 42%. Mean Na,K-ATPase activities ± SEM were 279 ± 58 _versus_ 198 ± 44 nmol inorganic P·h−1·μg DNA−1, _p_ = 0.05. However,

amiloride-sensitive potassium secretion after an acute potassium load of 20 μmol·min−1·kg−1 over 150 min was not enhanced (9.6 ± 1.8 _versus_ 8.9 ± 0.8 μmol·min−1·kg−1,

potassium-supplemented _versus_ control animals). We conclude that lower enzyme abundance is not primarily responsible for the newborn's lower potassium secretory capacity. We speculate

that the factor that limits secretion in the newborn during acute potassium loading does so by restricting catalytic turnover of the enzyme _in vivo_. SIMILAR CONTENT BEING VIEWED BY OTHERS

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AFFILIATIONS * Department of Pediatrics, School of Medicine, State University of New York at Stony Brook, Stony Brook, 11794–8111, New York John M Lorenz & Lyle E Browne * Department of

Biochemistry and Molecular Biophysics, College of Physicians and Surgeons, Columbia University, New York, 10032, New York Margery A Manuli Authors * John M Lorenz View author publications

You can also search for this author inPubMed Google Scholar * Margery A Manuli View author publications You can also search for this author inPubMed Google Scholar * Lyle E Browne View

author publications You can also search for this author inPubMed Google Scholar RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Lorenz, J., Manuli, M.

& Browne, L. The Role of Cortical Na,K-ATPase in Distal Nephron Potassium Secretion by the Immature Canine Kidney. _Pediatr Res_ 30, 457–463 (1991).

https://doi.org/10.1203/00006450-199111000-00012 Download citation * Received: 12 April 1990 * Accepted: 26 June 1991 * Issue Date: 01 November 1991 * DOI:

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