EFFECTS OF ISOFLURANE INHALATION ANESTHESIA ON MOUSE ECG

General anesthesia is important for pharmacological studies in laboratory animals. Although a number of transgenic animals have been reported, basic analyses concerning mouse ECG and heart rate variability (HRV) have not been rigorously examined. In the present study, we analyzed the effects of isoflurane as an inhalational anesthetic agent on ECG in C57BL6 mice, which have highly homogeneous genetic background. With 2% isoflurane anesthesia, the heart rate was acceptable (~500 bpm). Interestingly, C57BL6 mice showed relatively large standard deviation (57.3 bpm). Our data indicates that C57BL6 mice have various heart rates, although its genetic background is homogeneous. Higher concentrations of isoflurane resulted in a decreased heart rate, in a dose-dependent manner, and resulted in a marginal response to the sympathetic β-blocker, propranolol. Furthermore, we evaluated HRV as well as ECG parameters in mice. Our results indicate the importance of selecting an anesthesia for pharmacological studies using standard ECG parameters and HRV in C57BL6 mice. We provide basic ECG parameters from a large population of C57BL6 mice, which are fundamental baseline data for cardiovascular physiology. Hirosaki Med.J. 66:1―7,2015