Heart rate as a predictor of metabolic rate in heterothermic bats

Abstract

While heart rate (fH) has been used as an indicator of energy expenditure, quantitative data showing the relationship between these variables are only available for normothermic animals. To determine whether fH also predicts oxygen consumption (V. O2) during torpor, we simultaneously measured V. O2, fH and subcutaneous body temperature (Tsub) of a hibernator, Gould's long-eared bats (Nyctophilus gouldi, 9 g, N=18), at ambient temperatures (Ta) between 0 and 25°C. At rest, fH of normothermic resting bats was negatively correlated with Ta, with maximum fH of 803 beats min-1 (Ta=5°C). During torpor, the relationship between fH and Ta was curvilinear, and at low Tsub (6°C), fH fell to a minimum ..