Meeting Abstract
Bat wings possess a large number of joints that are controlled relatively independently by muscles within the wing. Previous studies have shown that the temperature of bat wings is lower than that of the body during flight with the distal wing approaching air temperature. Bats are also known to use daily torpor and may initiate flight with reduced body temperatures (Tb). Muscle mechanical performance declines with temperature; thus, low muscle temperature (Tm) could potentially influence flight performance. The bat extensor carpi radialis longus (ECRL) is a forearm extensor that is critical to extending the wings and keeping them open during downstroke. Because this distal wing muscle likely operates at a Tm less than Tb, we predicted that the performance of the bat ECRL would be less temperature dependent than that of other vertebrate skeletal muscles. We measured in vitro the isometric and isotonic contractile properties of the ECRL in Carollia perspicillata, from 22 to 37 °C at 5 °C intervals. The Q10’s for shortening velocity were approximately 1.2, 1.4, and 2.0 for the temperature ranges of 32 – 37, 27 – 32, and 22 – 27 °C, respectively. Similarly, the ½ relaxation time from a tetanus had Q10’s of approximately 1.3, 1.4, and 1.9 for the same temperature intervals. By comparison, in the limb muscles of other mammals, the Q10’s reported for Vmax are approximately 1.8 between 25 and 35 °C, and the Q10’s for relaxation times are greater than 2.0 over this temperature range. These findings suggest that the wing muscles in bats may be adapted to maintain function across a wider range of temperatures than are limb muscles from other mammals.
