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First published online December 28, 2007
Journal of Experimental Biology 211, 180-186 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.013466
Research Article, Motor Systems |
A spatially explicit model of muscle contraction explains a relationship between activation phase, power and ATP utilization in insect flight
1 Department of Biology, University of Washington, Seattle, WA 98195, USA
2 Department of Bioengineering, University of Washington, Seattle, WA 98195,
USA
* Author for correspondence (e-mail: bcwt{at}u.washington.edu)
Accepted 4 October 2007
Summary
Using spatially explicit, stochastically kinetic, molecular models of muscle force generation, we examined the relationship between mechanical power output and energy utilization under differing patterns of length change and activation. A simulated work loop method was used to understand prior observations of sub-maximal power output in the dominant flight musculature of the hawkmoth Manduca sexta L. Here we show that mechanical work output and energy consumption (via ATP) vary with the phase of activation, although they do so with different phase sensitivities. The phase relationship for contraction efficiency (the ratio of power output to power input) differs from the phase relationships of energy consumption and power output. To our knowledge, this is the first report to suggest that ATP utilization by myosin cross-bridges varies strongly with the phase of activation in muscle undergoing cyclic length changes.
Key words: spatially explicit modeling, work loop, phase, flight, muscle power, Manduca sexta
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