Meeting Abstract
P3.205 Tuesday, Jan. 6 Energy metabolism, body temperature and non-shivering thermogenesis in bats acclimating to simulated winter conditions. GUTOWSKI, J.; WOJCIECHOWSKI, M.S.*; Nicolaus Copernicus University, Torun, Poland; Nicolaus Copernicus University, Torun, Poland mwojc@umk.pl
To test the predictions that 1) bats decrease their lower critical temperature (Tlc) in response to seasonal changes in ambient conditions, and 2) that winter-acclimated bats increase their capacity for non-shivering thermogenesis (NST), we measured metabolic rate (MR), body temperature (Tb) and NST in 6 Myotis myotis during acclimation to simulated changes in ambient conditions. MR (VO2 by indirect calorimetry) and Tb were measured simultaneously at ambient temperatures (Ta) between 5 °C and 38 °C. Capacity for NST was measured at Ta=20±2 °C following injection of noradrenaline (NA). The same individuals were tested in autumn, winter and spring. In autumn and spring, bats were housed indoors, in flight cages and fed daily ad libitum; the photoperiod was natural. In winter, bats hibernated in an artificial hibernaculum and were fed every five days. The bats’ resting MR did not change with season (F(2,16)=1.63, p>0.05, 7.21±0.80 mWg-1). However, mean euthermic Tb decreased from ~36.6 °C and ~37.0 °C, in autumn and spring, to ~36.1 °C in winter (F(2,66)=4.51, p<0.05). This resulted in winter Tlc dropping by ~4 °C and ~2 °C compared to autumn and spring, respectively. VO2 following NA did not change, but maximum Tb was higher after NA injection in winter and in spring than in autumn (F(2,20)=4.81, p<0.05). Our data suggest that in winter M. myotis saves energy by lowering its euthermic Tb. Higher maximum Tb following NA injection indicates increasingly effective use of NST. The changes also indicate frugal energy expenditure during intra-hibernation euthermic episodes.
