Activity index from continuous telemetry in a mouse model of voluntary wheel exercise training

Mouse models are now widely used for studying gene function and facilitating drug discovery and development within the pharmaceutical industry. The availability of murine biomedical signals brings new challenges in terms of obtaining recordings, signal processing and analysis. Heart rate variability (HRV) is predictive of prognosis in cardiovascular disease states, especially heart failure, and also provides a measure of autonomic function. Reliable estimation of HRV metrics are of interest to those carrying out biomedical research with mouse models. A voluntary murine wheel running model is employed to test how HRV is mediated by the autonomic nervous system. Telemeters are used to measure the blood pressure waveform at 500 Hz in freely moving mice, providing a time series of cardiac interbeat intervals. An activity index is derived from the heart rate signal and compared with an independent measure of three activity states: (i) rest; (ii) activity; and (iii) exercise.