[A study on heart weight and electrocardiogram of germfree, ex-germfree and conventional ICR mice (author's transl)].

The heart weight of germfree mice has been reported to be lighter than that of conventional mice. The difference in heart function between these mice, however, has not been well investigated. In the present study, we recorded ECGs of germfree, ex-germfree and conventional mice anesthetized with pentobarbitone sodium and weighed the hearts of these animals. On ECGs, there was no significant difference between germfree and conventional mice except QT and PP intervals, which were shorter in male germfree mice than those in male conventional mice. It was found that the heart weight of germfree mice was significantly lighter than that of conventional mice in both sexes. It was concluded that although the heart weight between germfree and conventional mice was different, the heart function evaluated using the ECG was not.