Effect of BAY K 8644 on cytosolic free calcium in isolated rabbit gall-bladder epithelial cells.
Rabbit gall-bladder epithelial cells were isolated by a combination of Ca2+ omission, enzymatic treatment, and mechanical detachment and had a viability of 96-98% and well preserved morphology. Measurements of cytosolic free Ca2+ concentration ([Ca2+]i) in these cells with the Ca2+-fluorescent indicator fura-2 demonstrated a resting [Ca2+]i level of 115 +/- 12 nM. When used in concentrations which inhibit rabbit gall-bladder isosmotic NaCl absorption (1-100 microM), the Ca2+-channel activator BAY K 8644 caused a dose-dependent increase in the epithelial [Ca2+]i to a maximal value of 850 nM. The effect was dependent on extracellular Ca2+, and was not altered by 1 microM L-verapamil. Depolarization of the epithelial cells with KCl had no effect on [Ca2+]i. The results suggest that BAY K 8644 activates a Ca2+ influx which is not dependent on voltage-gated channels. Cytosolic Ca2+ may be involved in the regulation of isosmotic NaCl absorption in the mammalian gall-bladder.
Bouchelouche
P N
PN
Department of Clinical Chemistry, Herlev Hospital, Copenhagen, Denmark.
Hainau
B
B
Frederiksen
O
O
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology*; D000818:Animals; D001572:Benzofurans; D002118:Calcium / Q000032:analysis / Q000378:metabolism*; D002469:Cell Separation / Q000379:methods; D003592:Cytophotometry; D003600:Cytosol / Q000032:analysis / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D005260:Female; D016257:Fura-2; D005704:Gallbladder / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D011817:Rabbits; D014700:Verapamil / Q000494:pharmacology
D001572:Benzofurans; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D014700:Verapamil; D002118:Calcium; D016257:Fura-2