2.9 Statistical analysis
All patch clamp recorded data were analyzed using Clampfit 10.6 (Molecular Devices, USA), OriginPro 8.0 (Origin Lab, USA) and Adobe Illustrator 10 (Adobe, USA). The concentration-response curve was fitted by the logistic equation y =A 2+(A 1-A 2)/[1+(x /x 0)p ], where x is the drug concentration, and p is the Hill coefficient. All data are expressed as the means ± SEM. One-way ANOVA followed by multiple-comparison test was used to evaluate multiple test treatments. A value of p<0.05 was considered to be statistically significant. IC50 denotes the concentration determined for half-maximal inhibitory effects. In the figures, the designations for p values are: *p<0.05, **P<0.01 and ***P<0.001 respectively.

Results
The four groups of experiments conducted assessed the mechanistic basis for the clinical reports bearing upon cardiac safety of HCQ, whether applied alone or in combination with AZM.