Transducing chemical energy into mechanical function: a comparative view.
The energetics of muscle contraction can be understood in terms of the major cellular ATPases. The twitch isometric transduction efficiency is relatively constant across muscle types and species. Although many of the factors that alter the shape of the enthalpy:load relation in isotonic twitch contractions have been identified our molecular understanding is unsatisfactory and more studies are needed of mammalian muscles working closer to 37 degrees C. The thermodynamic efficiency of CB activity seems quite high, probably in excess of 70%. During maintained (tetanic) force there can be greater than a 1000 fold difference in energy usage across muscle types and there are factors that can down regulate CB activity: these factors remain to be fully identified in both skeletal and smooth muscles. The very diversity of muscle types and the different biochemical solutions that have emerged to match energy supply and demand should lead to important insights into the contractile mechanism. The corollary however also applies, it may be dangerous to take results obtained in one muscle type under a particular set of conditions, and extrapolate those findings to muscles in general.
Gibbs
C L
CL
Department of Physiology, Monash University, Clayton. Vic.
Wendt
I R
IR
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D004734:Energy Metabolism; D007537:Isometric Contraction; D009132:Muscles / Q000502:physiology*; D013816:Thermodynamics
D000251:Adenosine Triphosphatases