Fig. 4. Ethanolic (30%) extract of Spirodela polyrhiza (SPEtOH) specifically inhibits the calcium-activated Cl– current (ICaCC) but not cystic fibrosis transmembrane conductance regulator (CFTR)-mediated Cl– current (ICFTR) in Calu-3 cells.
(A) Representative traces of ICaCC following activation by 600 nM intracellular free calcium and inhibition by SPEtOH (0.3, 1, and 3 mg/ml) and 2-(4-chloro-2-methylphenoxy)-N-[(2-methoxyphenyl)methylideneamino]-acetamide (Ani9, 1 μM). The holding potential was –60 mV and 4-s step pulses (each 10 mV, –100 to +100 mV) were applied every second. (B) Bar graph showing normalized ICaCC and its inhibition by SPEtOH, which was calculated as IExt/Ictrl × 100% at +100 mV. Data are presented as the mean ± standard error of mean. ****p < 0.0001 compared to the control (n = 10). (C) A typical trace showing the amplitudes of ICFTR and the effects of serially treating Calu-3 cells with 1 mg/ml SPEtOH and 10 μM CFTRinh-172. The results show that ICFTR was not modulated by SPEtOH; however, it was completely inhibited by CFTRinh-172. (D) Representative current (I)/voltage (V) curves for ICFTR after treatment with SPEtOH and 10 μM CFTRinh-172. (E) Normalized current amplitude of ICFTR at 100 mV. Data are presented as the mean ± SEM. ****p < 0.0001 compared to the control (n = 6).