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Media type:
E-Article
Title:
cAMP-induced changes of apical membrane potentials of confluent H441 monolayers
Contributor:
Lazrak, Ahmed;
Matalon, Sadis
Published:
American Physiological Society, 2003
Published in:
American Journal of Physiology-Lung Cellular and Molecular Physiology, 285 (2003) 2, Seite L443-L450
Language:
English
DOI:
10.1152/ajplung.00412.2002
ISSN:
1040-0605;
1522-1504
Origination:
Footnote:
Description:
We recorded apical membrane potentials ( Va) of H441 cells [a human lung cell line exhibiting both epithelial Na+ (ENaC) and CFTR-type channels] grown as confluent monolayers, using the microelectrode technique in current-clamp mode before, during, and after perfusion of the apical membranes with 10 μM forskolin. When perfused with normal Ringer solution, the cells had a Va of -43 ± 10 mV (means ± SD; n = 31). Perfusion with forskolin resulted in sustained depolarization by 25.0 ± 3.5 mV (means ± SD; n = 23) and increased the number, open time, and the open probability of a 4.2-pS ENaC. In contrast to a previous report (Jiang J, Song C, Koller BH, Matthay MA, and Verkman AS. Am J Physiol Cell Physiol 275: C1610–C1620, 1998), no transient hyperpolarization was observed. The forskolin-induced depolarization of Va was almost totally prevented by pretreatment of monolayers with 10 μM amiloride or by substitution of Na+ ions in the bath solution with N-methyl-d-glucamine. These findings indicate that cAMP stimulation of Na+ influx across H441 confluent monolayers results from activation of an amiloride-sensitive apical Na+ conductance and not from Va hyperpolarization due to Cl- influx through CFTR-type channels.