Sex dependent electrocardiogram (ECG) changes in anthracycline-treated mice

Single administration of 2 mg/kg Violamycin B I induces a cardiomyopathy in mice associated with prolongation of the QRS- and S alpha T-segment in the electrocardiogram (ECG). The changes of the QRS-segment were independent of sex (males: control 6.10 ms +/- 0.41, 8 days after Violamycin B I application 9.13 ms +/- 1.16; females: control 6.41 ms +/- 0.46, 8 days after Violamycin B I application 8.78 ms +/- 0.83), the prolongation of the S alpha T-segment in males (control 3.52 ms +/- 0.21, 8 days after Violamycin B I application 11.18 ms +/- 2.25) was significantly stronger than in females (control 3.46 ms +/- 0.20, 8 days after Violamycin B I application 8.22 ms +/- 1.04). A reduction of the acetylcholine effect in the heart tissue could be responsible for the sex dependent prolongation of the S alpha T segment, because acetylcholine accelerates the repolarization which is part of the S alpha T segment, and the heart of females seems to have a greater amount of acetylcholine storage.