Surface epithelium and gland cells from human trachea were cultured on porous-bottom inserts and loaded with fura 2 to permit measurement of the intracellular calcium concentration ([Ca2+](i)). Short-circuit current (I(sc)), an index of transepithelial active ion transport, was measured on cells from the same cultures. Surface epithelial [Ca2+](i) of 82 ± 15 nM was increased transiently by isoproterenol, histamine, and bradykinin with maximal increases of 88 ± 17, 480 ± 149, and 978 ± 214 nM (n = 15), respectively. Baseline [Ca2+](i) in cultured gland cells of 68 ± 11 nM was increased transiently by isoproterenol, histamine, methacholine, and bradykinin with maximal increases of 105 ± 19, 233 ± 47, 327 ± 121, and 634 ± 151 nM (n = 17-21), respectively. In both cell types, mediators that increased [Ca2+](i) also increased I(sc) with a time course identical to the increase in [Ca2+](i). Pretreatment with the calcium chelator, 1,2- bis-(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid, acetoxymethyl ester (BAPTA-AM), had no effect on basal I(sc) or transepithelial resistance but markedly inhibited both the I(sc) and [Ca2+](i) responses to agonists. Forskolin (10-5 M), 3-isobutyl-1-methylxanthine (10-3 M), dibutyryl adenosine 3',5'-cyclic monophosphate (10-3 M), and 8-(4-chlorophenylthio)- cAMP (10-3 M) had no or only trivial effects on I(sc) and [Ca2+](i). We suggest that mediators increase I(sc) across human airway epithelium by activating Ca-dependent basolateral K channels, resulting in hyperpolarization and an increased driving force for Cl exit through apical membrane Cl channels.
|ジャーナル||American Journal of Physiology - Lung Cellular and Molecular Physiology|
|出版ステータス||Published - 1993|
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine
- Physiology (medical)
- Cell Biology