Abstract
Rabbit gall-bladder epithelial cells were isolated by a combination of Ca 2+ omission, enzymatic treatment, and mechanical detachment and had a viability of 96–98% and well preserved morphology. Measurements of cytosolic free Ca 2+ concentration ([Ca 2+] i) in these cells with the Ca 2+-fluorescent indicator fura-2 demonstrated a resting [Ca 2+] i level of 115±12 nM. When used in concentrations which inhibit rabbit gall-bladder isosmotic NaCl absorption (1–100μM), the Ca 2+-channel activator BAY K 8644 caused a dose-dependent increase in the epithelial [Ca 2+] i to a maximal value of 850 nM. The effect was dependent on extracellular Ca 2+, and was not altered by 1μM L-verapamil. Depolarization of the epithellal cells with KCl had no effect on [Ca 2+] i. The results suggest that BAY K 8644 activates a Ca 2+ influx which is not dependent on voltage-gated channels. Cytosolic Ca 2+ may be involved in the regulation of isosmotic NaCl absorption in the mammalian gall-baldder.
Published Version
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