Fig. 3. Downregulation of inward-rectifying K⁺ channel in ρ0 myoblasts.

(A) Representative chart trace recordings of inward-rectifying K⁺ current (I_Kir) in symmetrical KCl solution. For whole-cell patch-clamp recordings, the current was obtained by step depolarizing pulse ranging from −140 mV to 70 mV at a holding potential of 0 mV. (B) Average I–V relationship curve for the peak I_Kir from −140 to 70 mV between control (n=13) and ρ0 myoblasts (n=13). ^*p<0.05. (C) Immunoblot assay of KIR2.1 and β-actin expression in control and ρ0 myoblasts. KIR2.1 signals were normalized to the β-actin signal, and mean values are displayed as bar graphs (n=3). ^*p<0.05. Data are means±standard error of the mean. (D) Average I–V relationship curve of I_Kir following treatment with antimycin A (n=7) and in control myoblasts (n=7) in normal myocytes. (E) Current density of I_Kir at −120 mV. ^**p<0.01. All data are presented as the mean±standard error of the mean.