Seasonal biochemical plasticity of a flight muscle in a bat, Murina leucogaster

Cellular and biochemical responses of the pectoral muscle to variation in s easonal activity were studied in the bat, Murina leucogaster ognevi. We col lected bats in mid-hibernation (February), end-hibernation (April), and mid -summer (August) to track major activity periods in their annual cycle. Our findings indicated that myofiber cross-sectional area decreased to 68% bet ween mid- and end-hibernation, but returned to the winter level in mid-summ er. Total soluble protein and total RNA concentrations were not altered ove r these sampling periods. Oxidative potential gauged by citrate synthase ac tivity increased 1.47-fold from mid- to end-hibernation and then remained a t the similar level in mid-summer. Glycolytic potential gauged by lactate d ehydrogenase activity changed little between mid- and end-hibernation but i ncreased 1.42-fold in summer, compared with the winter level. Thus, the myo fibers underwent disuse atrophy during hibernation, while enzymatic catalyt ic function recovered towards the level of mid-summer. (C) 2000 Elsevier Sc ience Inc. All rights reserved.