AJP - Cell Physiology, Vol 262, Issue 3 C644-C655, Copyright © 1992 by American Physiological Society

ARTICLES

Effects of bradykinin on Na+ and Cl- transport in human nasal epithelium

L. L. Clarke, A. M. Paradiso, S. J. Mason and R. C. Boucher
Department of Medicine, University of North Carolina, Chapel Hill 27599.

Human nasal epithelium (HNE) is a Na+ absorptive epithelium but establishes a baseline Cl- secretory current in the presence of amiloride (10(-4) M, luminal). We compared the effects of an inflammatory mediator, bradykinin (BK), on ion transport in primary cultures of HNE using double-barreled Cl(-)-selective microelectrodes. In untreated HNE, BK (10(-5) M) transiently increased the equivalent short-circuit current (Ieq). Maximal Ieq occurred with hyperpolarization of the transepithelial potential difference (Vt), which was associated with hyperpolarization and decreased resistance of the basolateral membrane; a subsequent depolarization of Vt was observed that was associated with depolarization and decreased resistance of the apical membrane. Removal of bath Cl- did not affect the BK-induced Ieq response. In amiloride-treated HNE, the electrical pattern of the BK-induced response was identical, but the magnitude of the Ieq was reduced by 54% and the change in Ieq could be abolished by removal of bath Cl-. Equivalent-circuit analysis of the response in amiloride-treated tissues indicated activation of a hyperpolarizing conductance in the basolateral membrane, followed 20-30 s later by activation of an apical Cl- conductance. We conclude that BK stimulates both Na+ absorption in untreated HNE and Cl- secretion in amiloride-treated HNE by activating a basolateral (K+) conductance. Analysis of the entire Ieq response under both conditions also suggested that BK induces a delayed activation of apical membrane Na+ and Cl- conductances.

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