AJP - Lung Cellular and Molecular Physiology, Vol 257, Issue 2 125-L129, Copyright © 1989 by American Physiological Society

ARTICLES

Alpha-adrenergic regulation of Na-Cl cotransport in human airway epithelium

C. M. Liedtke
Department of Pediatrics, Rainbow Babies and Children Hospital, Cleveland, Ohio 44106.

The demonstration of abnormal beta-adrenergic and cAMP-modulated apical Cl- channels in cystic fibrosis (CF) airway epithelial cells suggests that other transporters, which are required for Cl- secretion, may also be abnormally regulated. A basolateral cotransporter was investigated by determining the initial rate of 36Cl efflux from cells isolated from CF nasal polyps or trachea and non-CF trachea. Cells were preequilibrated with radioactive tracer at 25 degrees C, and tracer transport was initiated by 10-fold dilution of an aliquot of cells in radioisotope-free medium. The initial rate of Cl transport was calculated from the linear portion of the efflux curves. In CF and non-CF cells, base-line Cl- transport was not blocked by furosemide but was stimulated twofold by l-epinephrine in Ca2+-deficient and Ca2+-replete transport medium. In both types of cells, furosemide blocked 70 and 77%, respectively, of the stimulated Cl- transport. Prazosin, an alpha 1-adrenergic antagonist, blocked the effects of l-epinephrine and methoxamine, an alpha 1-adrenergic agonist, stimulated prazosin- and furosemide-sensitive Cl transport. Ionomycin mimicked the effects of l-epinephrine. l-Isoproterenol, a beta-adrenergic agonist, did not affect Cl transport. The results of this study indicate an alpha 1-adrenergic stimulation of furosemide-sensitive Cl transport in human airway epithelium that functions normally in CF airway epithelial cells. The transport mechanism is probably a Na-Cl or Na-K-2Cl cotransport located in the basolateral membrane and requires elevated intracellular Ca2+ for activation.

This article has been cited by other articles:

				J. M. Pinto, P. Assanasen, F. M. Baroody, E. Naureckas, and R. M. Naclerio {alpha}-Adrenoreceptor blockade with phenoxybenzamine does not affect the ability of the nose to condition air J Appl Physiol, July 1, 2005; 99(1): 128 - 133. [Abstract] [Full Text] [PDF]

				G. O. Andersen, M. Enger, G. H. Thoresen, T. Skomedal, and J.-B. Osnes alpha 1-Adrenergic activation of myocardial Na-K-2Cl cotransport involving mitogen-activated protein kinase Am J Physiol Heart Circ Physiol, August 1, 1998; 275(2): H641 - H652. [Abstract] [Full Text] [PDF]