Skeletal muscle pH dynamics during arousal from hibernation measured by31P NMR spectroscopy |
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Authors: | M D McArthur C C Hanstock A Malan L C H Wang P S Allen |
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Institution: | (1) Department of Zoology, University of Alberta, T6G 2E9 Edmonton, Alberta, Canada;(2) Department of Applied Sciences in Medicine, University of Alberta, T6G 2E9 Edmonton, Alberta, Canada;(3) Laboratoire d'Etude des Régulations Physiologiques (associated with Université Louis Pasteur), CNRS, 67087 Strasbourg, France |
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Abstract: | Summary The time-course of changes in skeletal muscle pH during arousal from hibernation in the Columbian ground squirrel was studied using31P NMR spectroscopy. In hibernation (T
re 7–9°C), shoulder/neck muscle pH was 7.45±0.03 and Im was 0.60. In euthermia (T
re 37°C), muscle pH was 7.24±0.05 and Im was 0.75. Thus the overall pH-temperature coefficient was-0.009 pH units/°C, indicating acidification of the muscle in hibernation. During the transition from hibernation to euthermia, however, the muscle shows a nonlinear pattern of pH change. In early arousal (T
sh<20–25°C,T
re<15°C) muscle pH does not change and muscle Im increases to 0.72. In later arousal (T
sh>20–25°C,T
re>15°C) muscle pH decreases gradually toward the euthermic value and muscle Im increases only slightly from 0.72 to 0.75. These results support the hypothesis that intracellular acidification of the muscle, present during hibernation, is reversed in early arousal. This may facilitate an increase in muscle metabolism and the contribution of maximal shivering thermogenesis to rewarming of the animal.Abbreviations Im
dissociation ratio of protein imidazole buffergroups
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NST
non-shivering thermogenesis
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BAT
brown adipose tissue
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dp H/dT
temperature coefficient of pH
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pH
i
intracellular pH
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31
P NMR
31Phosphorus nuclear magnetic resonance
- P
i
chemical shift of inorganic phosphate relative to PCr
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PCr
phosphocreatine
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T
b
body temperature
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T
re
rectal temperature
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T
sh
subcutaneous shoulder temperature
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T
a
ambient temperature |
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Keywords: | Ground squirrel 31Phosphorus NMR Skeletal muscle pH Alpha-imidazole Arousal from hibernation |
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