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Thermogenesis and motor recruitment of the pectoral muscle during shivering in arousing bats murina leucogaster

2001; Taylor & Francis; Volume: 5; Issue: 1 Linguagem: Inglês

10.1080/12265071.2001.9647579

1226-5071

Inho Choi, Youn Sun Lee, Yung Keun Oh, Noh‐Pal Jung, Byoung Joo Gwag, Hyung‐Cheul Shin,

Physiological and biochemical adaptations

Temperate‐resident bats exhibit a circadian cycle of torpor and arousal in summer. The physiological role and selective advantage of torpor as an energy saving mechanism have been received much attention by hibernation biologists. However, despite the significance of the recovering euthermic function, the arousal process and mechanism in these animals have been poorly addressed. In this study, we investigated thermogenic and motor activities of a local bat species Marina leucogaster during arousal by simultaneously examining oxygen consumption rate, body temperature (Tb) and pectoral electromyography (EMG). We found that Tb of the torpid bats (12–14°C) was augmented slowly by nonshivering mechanism during the initial awakening phase. The pectoral shivering, gauged by EMG activity, occurred between 17°C and 38°C. Over this Tb range of shivering, heat was produced at a rate of 0.145 kcal kg‐1 min‐1 to raise 1°C Tb per min. Shivering was most intensive at 30–35°C where both EMG amplitude and spike frequency were the highest. Activation of the pectoral myofibers seemed to be controlled in a manner that motor units were recruited from smaller to larger sizes, with greater synchronization, as muscle shivering became intensive with increasing Tb.