Fig. 3.

Effect of Iban on BK_Ca-channel activity at different potentials in MDCK cells. For this purpose, cells were exposed to high-K⁺ solution containing 1.8 mM CaCl₂ and held at different levels of membrane potentials. (A) The I–V relationships of BK_Ca channels obtained in the absence (■) and presence (□) of 10 μM Iban. Values are means ± SEM for n = 15–18 cells in each point). (B) The relationships between normalized channel activity and membrane potential obtained before and after addition of 10 μM Iban. Values are means ± SEM for n = 12–15 cells in each point. ■: control (black); □: in the presence of 10 μM Iban (blue). (C) Iban (10 μM)-induced Inhibition of BK_Ca-channel activity at various concentrations of internal Ca²⁺. In this set of experiments, inside-out current recordings were performed and different concentrations (0.01, 0.1 and 1 μM) of Ca²⁺ in the bath before (blue bars) and after 10 μM Iban (red bars) were applied to the bath. Values are means ± SEM for 6–8 cells in each group. ^*Significantly different from controls (P < 0.05). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)