Sm. Wilson et al., CALCIUM-DEPENDENT REGULATION OF MEMBRANE ION PERMEABILITY IN A CELL-LINE DERIVED FROM THE EQUINE SWEAT GLAND EPITHELIUM, Comparative biochemistry and physiology. Part A, Physiology, 111(2), 1995, pp. 215-221
We measured the rates of I-125(-) and Rb-86(+) efflux from preloaded,
cultured equine sweat gland cells. The calcium ionophore ionomycin inc
reased the efflux of both isotopes, Anion efflux was unaffected by Ba2
+, but this cation inhibited Rb-86(+)-efflux, suggesting that [Ca2+](i
)-activated potassium channels were present. Activation of these chann
els was not, however, important for the efflux of anions. We measured
I-125(-) efflux from valinomycin-depolarised cells in which anion cotr
ansport was inhibited. Changes in I-125(-) efflux reflect changes in a
nion permeability under these conditions, and ionomycin caused a clear
permeability increase that was abolished by the anion channel blocker
diphenylamine-2-carboxylate. ATP and UTP increased the efflux of both
isotopes, suggesting that type P-2U purine receptors allow these nucl
eotides to regulate membrane permeability.