Fig. 1

Effects of testosterone supplementation on ECG and ECG parameters in castrated male rats. a Representative time series changes in RR intervals and QT intervals by intraperitoneally administered testosterone (1000 µg/kg/day), and ECG records at the time indicated (a–c). A sample of ECG on day 0 and day 13 are shown in inset. b ECG parameters of RR interval (ms), PR time (ms), QRS time (ms) and QT interval (ms) on day 0 (control), day 1 and day 7. Data are presented as the mean value ± SEM. *p < 0.05 vs day 0