The telemetric monitoring of heart rate, locomotor activity, and body temperature in mice and voles (Microtus arvalis) during ambient temperature changes.

We have studied the physiological and behavioural responses in small rodents to ambient alterations. For this purpose, voles and mice were exposed to relatively low (12 degrees C) and high (35 degrees C) ambient temperatures, and heart rate (HR), locomotor activity (LA) and body temperature (BT) were recorded using telemetry system. The control HR (at 24 degrees C) of voles was lower than that of mice. The 'heat exposure' decreased HR to 85.0 +/- 3.3% in voles, and to 78.0 +/- 3.2% in mice compared with the mean HR of the same time in the control day. The 'cold exposure' increased the HR to 131.9 +/- 8.8% in voles, and 119 +/- 10.9% in mice. The decreasing rate of HR in heat exposure was smaller in voles than mice, and in cold exposure the increased rate was larger in voles than mice. Cold exposure decreased BT in both species; 96.1 +/- 0.5% in voles and 93.7 +/- 1.0% in mice. The LA was not changed significantly by heat exposure in either species, but was partially increased by cold exposure. These results demonstrate that telemetry was helpful for qualitative and quantitative behavioural studies in small rodents, and confirmed that the physiological and behavioural responses to ambient temperature changes differed between these animals.