Fig 8. Effect of IL-6 on guinea pig ERG expression and action potential in ventricular myocytes.

A, qRT-PCR was used to determine guinea pig ether-á-go-go-related gene (ERG) mRNA expression in control ventricular myocytes and in myocytes pre-treated with IL-6 (20 ng/ml). B, Western blot assay of guinea pig ERG protein expression in control (Lane 1) and IL-6 pretreated (for 40 mins) myocytes (Lane 2). Values were normalized to the GAPDH signal and expressed as % of control or in the absence of IL-6. Each sample was analyzed in triplicate. 150 kDa and 135 kDa ERG bands were identified in lane 1 but were significantly less dense in lane 2 loaded with IL-6 (20 ng/ml) pretreated ventricular myocytes’ lysate. C, Comparison of the relative abundance of the 150 kDa ERG band in untreated and IL-6 treated myocytes. D, Comparison of the relative abundance of the 135 kDa ERG band in untreated and IL-treated myocytes. The 37 kDa bands represent GAPDH. E, Action potential waveforms recorded in control myocytes (basal conditions without IL-6, Black trace) and in the presence of IL-6 alone (Red trace), IL-6+IL-6R (Grey trace), IL-6+IL-6R+JAK inhibitor-1 (Cyan trace) and another JAK inhibitor AG490 (Orange trace). F, Pretreatment of myocytes with IL-6 and IL-6+IL-6R significantly prolonged APD₉₀ and JAK inhibitor I and AG490 completely reversed the prolongation of the action potential.