TY - JOUR
T1 - Regional thermal specialisation in a mammal
T2 - temperature affects power output of core muscle more than that of peripheral muscle in adult mice (Mus musculus)
AU - James, Rob S.
AU - Tallis, Jason
AU - Angilletta, Michael
N1 - Funding Information:
Thanks to Mark Bodycote, Bethan Grist and Roy Petticrew for technical assistance. This research was supported by Coventry University, UK. Many thanks to the referees for their constructive comments.
Publisher Copyright:
© 2014, Springer-Verlag Berlin Heidelberg.
PY - 2015/1/1
Y1 - 2015/1/1
N2 - In endotherms, such as mammals and birds, internal organs can specialise to function within a narrow thermal range. Consequently, these organs should become more sensitive to changes in body temperature. Yet, organs at the periphery of the body still experience considerable fluctuations in temperature, which could select for lower thermal sensitivity. We hypothesised that the performance of soleus muscle taken from the leg would depend less on temperature than would the performance of diaphragm muscle taken from the body core. Soleus and diaphragm muscles were isolated from mice and subjected to isometric and work-loop studies to analyse mechanical performance at temperatures between 15 and 40 °C. Across this thermal range, soleus muscle took longer to generate isometric force and longer to relax, and tended to produce greater normalised maximal force (stress) than did diaphragm muscle. The time required to produce half of maximal force during isometric tetanus and the time required to relax half of maximal force were both more sensitive to temperature in soleus than they were in diaphragm. However, thermal sensitivities of maximal force during isometric tetani were similar for both muscles. Consistent with our hypothesis, power output (the product of speed and force) was greater in magnitude and more thermally sensitive in diaphragm than it was in soleus. Our findings, when combined with previous observations of muscles from regionally endothermic fish, suggest that endothermy influences the thermal sensitivities of power output in core and peripheral muscles.
AB - In endotherms, such as mammals and birds, internal organs can specialise to function within a narrow thermal range. Consequently, these organs should become more sensitive to changes in body temperature. Yet, organs at the periphery of the body still experience considerable fluctuations in temperature, which could select for lower thermal sensitivity. We hypothesised that the performance of soleus muscle taken from the leg would depend less on temperature than would the performance of diaphragm muscle taken from the body core. Soleus and diaphragm muscles were isolated from mice and subjected to isometric and work-loop studies to analyse mechanical performance at temperatures between 15 and 40 °C. Across this thermal range, soleus muscle took longer to generate isometric force and longer to relax, and tended to produce greater normalised maximal force (stress) than did diaphragm muscle. The time required to produce half of maximal force during isometric tetanus and the time required to relax half of maximal force were both more sensitive to temperature in soleus than they were in diaphragm. However, thermal sensitivities of maximal force during isometric tetani were similar for both muscles. Consistent with our hypothesis, power output (the product of speed and force) was greater in magnitude and more thermally sensitive in diaphragm than it was in soleus. Our findings, when combined with previous observations of muscles from regionally endothermic fish, suggest that endothermy influences the thermal sensitivities of power output in core and peripheral muscles.
KW - Endotherm
KW - Force
KW - Power
KW - Temperature
KW - Tetanus
KW - Thermal sensitivity
UR - http://www.scopus.com/inward/record.url?scp=84945308563&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84945308563&partnerID=8YFLogxK
U2 - 10.1007/s00360-014-0872-6
DO - 10.1007/s00360-014-0872-6
M3 - Article
C2 - 25403362
AN - SCOPUS:84945308563
SN - 0174-1578
VL - 185
SP - 135
EP - 142
JO - Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
JF - Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
IS - 1
ER -