Intracellular Na+ and K+ activities and membrane conductances in the collecting tubule of Amphiuma

Détails

ID Serval
serval:BIB_77B76B91055E
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Intracellular Na+ and K+ activities and membrane conductances in the collecting tubule of Amphiuma
Périodique
Journal of General Physiology
Auteur(s)
Horisberger  J. D., Giebisch  G.
ISSN
0022-1295 (Print)
Statut éditorial
Publié
Date de publication
11/1988
Volume
92
Numéro
5
Pages
643-65
Notes
Journal Article
Research Support, U.S. Gov't, P.H.S. --- Old month value: Nov
Résumé
Membrane potentials and conductances, and intracellular ionic activities were studied in isolated perfused collecting tubules of K+-adapted Amphiuma. Intracellular Na+ (aNai) and K+ (aKi) activities were measured, using liquid ion-exchanger double-barreled microelectrodes. Apical and basolateral membrane conductances were estimated by cable analysis. The effects of inhibition of the apical conductance by amiloride (10(-5) M) and of inhibition of the basolateral Na-K pump by either a low K+ (0.1 mM) bath or by ouabain (10(-4) M) were studied. Under control conditions, aNai was 8.4 +/- 1.9 mM and aKi 56 +/- 3 mM. With luminal amiloride, aNai decreased to 2.2 +/- 0.4 mM and aKi increased to 66 +/- 3 mM. Ouabain produced an increase of aNai to 44 +/- 4 mM, and a decrease of aKi to 22 +/- 6, and similar changes were observed when the tubule was exposed to a low K+ bath solution. During pump inhibition, there was a progressive decrease of the K+-selective basolateral membrane conductance and of the Na+ permeability of the apical membrane. A similar inhibition of both membrane conductances was observed after pump inhibition by low K+ solution. Upon reintroduction of K+, a basolateral membrane hyperpolarization of -23 +/- 4 mV was observed, indicating an immediate reactivation of the electrogenic Na-K pump. However, the recovery of the membrane conductances occurred over a slower time course. These data imply that both membrane conductances are regulated according to the intracellular ionic composition, but that the basolateral K+ conductance is not directly linked to the pump activity.
Mots-clé
Animals Electrophysiology Kidney Tubules/*physiology Membrane Potentials Ouabain/pharmacology Potassium/*metabolism Sodium/*metabolism Urodela
Pubmed
Web of science
Open Access
Oui
Création de la notice
24/01/2008 13:38
Dernière modification de la notice
08/05/2019 20:37
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