Calcium-activated chloride fluxes in cultured NCL-SG3 sweat gland cells

Abstract

The dependence of chloride permeability of the human sweat gland cell line NCL-SG3 cell line on cytosolic free calcium ([Ca2+]i) was investigated. X-ray microanalysis, fura-2 fluorescence and patch clamp methodology were used. Carbachol and A23187 decreased cellular Cl and K for cells grown on permeable supports, but carbachol had no effect on cells grown on impermeable supports. In perforated patch experiments with impermeable supports, ATP and calcium ionophores increased the inward current (ic) whereas carbachol had no effect. ic was unaffected by cation channel blockers or removal of extracellular Na+ but was blocked by chloride channel blockers. Lowering bath Ca2+ decreased ic. On raising bath Ca2+ ic and [Ca2+]i responded with a transient rise which was not blocked by La3+ or D-600. La3+, but not D-600, blocked the entry of Mn2+. K+-depolarization and Bay-K-8644 had little effect on [Ca2+]i. The rise in [Ca2+]i may be mediated primarily via depletion operated Ca2+-channels. Irrespective of substrate NCL-SG3 cells have a chloride permeability which depends on [Ca2+]i.