Calcium-dependent regulation of membrane ion permeability in a cell line derived from the equine sweat gland epithelium.
We measured the rates of 125I- and 86Rb+ efflux from preloaded, cultured equine sweat gland cells. The calcium ionophore ionomycin increased the efflux of both isotopes. Anion efflux was unaffected by Ba2+, but this cation inhibited 86Rb(+)-efflux, suggesting that [Ca2+]i-activated potassium channels were present. Activation of these channels was not, however, important for the efflux of anions. We measured 125I- efflux from valinomycin-depolarised cells in which anion cotransport was inhibited. Changes in 125I- efflux reflect changes in anion 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 P2U purine receptors allow these nucleotides to regulate membrane permeability.
Wilson
S M
SM
Institute of Physiology, University of Glasgow, U.K.
Ko
W H
WH
Pediani
J D
JD
Rakhit
S
S
Nichol
J A
JA
Bovell
D L
DL
D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D000838:Anions / Q000378:metabolism; D001464:Barium / Q000494:pharmacology; D002034:Bumetanide / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D002460:Cell Line; D002463:Cell Membrane Permeability / Q000502:physiology; D004848:Epithelium / Q000378:metabolism; D006736:Horses; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics*; D017136:Ion Transport / Q000502:physiology; D015759:Ionomycin / Q000494:pharmacology; D012414:Rubidium Radioisotopes / Q000493:pharmacokinetics*; D013545:Sweat Glands / Q000166:cytology* / Q000378:metabolism; D014634:Valinomycin / Q000494:pharmacology
D000838:Anions; D007457:Iodine Radioisotopes; D012414:Rubidium Radioisotopes; D002034:Bumetanide; D014634:Valinomycin; D001464:Barium; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D015759:Ionomycin; D000255:Adenosine Triphosphate; D002118:Calcium