Effects of bradykinin on Na+ and Cl- transport in human nasal epithelium.
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.
Clarke
L L
LL
Department of Medicine, University of North Carolina, Chapel Hill 27599.
Paradiso
A M
AM
Mason
S J
SJ
Boucher
R C
RC
D000328:Adult; D000584:Amiloride / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D001920:Bradykinin / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism*; D046508:Culture Techniques; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D008433:Mathematics; D008564:Membrane Potentials / Q000187:drug effects; D012964:Sodium / Q000378:metabolism*; D014420:Turbinates / Q000187:drug effects / Q000378:metabolism*
D002712:Chlorides; D000584:Amiloride; D012964:Sodium; D001920:Bradykinin