Meeting Abstract

P2.189  Monday, Jan. 5  Determining Metabolized Fuel Source during Arousal from Hibernation using Stable Isotope Signatures in Breath. BOYLES, J.G.*; DUNBAR, M.B.; SCHULER, M.S.; STORM, J.J.; Indiana State Univ.; Univ. of Regina; Indiana State Univ.; Univ. of South Carolina Upstate jboyles3@indstate.edu

Fat-storing mammals rely mostly on a fixed energy source, white adipose tissue (WAT), to survive the hibernation period; however, brown adipose tissue (BAT) and food may lessen use of WAT in specific situations. BAT is used mainly for thermogenesis during arousal to raise body temperature to euthermic levels, but methods previously used to estimate the time course of BAT metabolism have poor temporal resolution and generally require subjects to be euthanized. Feeding during winter is possible in some situations, but it is unclear if fat-storing mammals metabolize food immediately to power euthermy, or if it is converted to WAT for later use. We conducted two experiments with wild little brown bats (Myotis lucifugus) to test the efficacy of a relatively new technique, stable isotope analysis of excurrent breath, in determining the metabolic fuel powering arousals from hibernation and the subsequent euthermic periods. First, we collected breath samples from 16 bats as they aroused from hibernation to determine if the change between BAT and WAT being metabolized for thermogenesis was detectable in excurrent breath. Second, we fed 48 euthermic bats mealworms with a known isotopic signature to determine if bats can quickly metabolize an exogenous energy source during euthermic bouts. The results of the first experiment suggest the isotopic signatures of WAT and BAT vary enough to be detectable in excurrent breath. The results of the second experiment suggest that despite a known atrophy of the digestive system during hibernation, bats begin metabolizing exogenous fuel sources shortly after feeding and continue to metabolize them for several hours.