|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
First published online July 6, 2005
Journal of Experimental Biology 208, 2641-2652 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01686
Does intracellular metabolite diffusion limit post-contractile recovery in burst locomotor muscle?
1 Department of Biology and Marine Biology, University of North Carolina
Wilmington, 601 South College Road, Wilmington, NC 28403-5915, USA
2 Department of Chemical and Biomedical Engineering, FAMU-FSU College of
Engineering, Tallahassee, FL 32310-6046, USA
* Author for correspondence (e-mail: kinseys{at}uncw.edu)
Accepted 12 May 2005
Post-metamorphic growth in the blue crab entails an increase in body mass that spans several orders of magnitude. The muscles that power burst swimming in these animals grow hypertrophically, such that small crabs have fiber diameters that are typical of most cells (<60 µm) while in adult animals the fibers are giant (>600 µm). Thus, as the animals grow, their muscle fibers cross and greatly exceed the surface area to volume ratio (SA:V) and intracellular diffusion distance threshold that is adhered to by most cells. Large fiber size should not impact burst contractile function, but post-contractile recovery may be limited by low SA:V and excessive intracellular diffusion distances. A number of changes occur in muscle structure, metabolic organization and metabolic flux during development to compensate for the effects of increasing fiber size. In the present study, we examined the impact of intracellular metabolite diffusive flux on the rate of post-contractile arginine phosphate (AP) resynthesis in burst locomotor muscle from small and large animals. AP recovery was measured following burst exercise, and these data were compared to a mathematical reaction–diffusion model of aerobic metabolism. The measured rates of AP resynthesis were independent of fiber size, while simulations of aerobic AP resynthesis yielded lower rates in large fibers. These contradictory findings are consistent with previous observations that there is an increased reliance on anaerobic metabolism for post-contractile metabolic recovery in large fibers. However, the model results suggest that the interaction between mitochondrial ATP production rates, ATP consumption rates and diffusion distances yield a system that is not particularly close to being limited by intracellular metabolite diffusion. We conclude that fiber SA:V and O2 flux exert more control than intracellular metabolite diffusive flux over the developmental changes in metabolic organization and metabolic fluxes that characterize these muscles.
Key words: muscle fiber, fiber growth, diffusion, metabolic modeling, reaction–diffusion, exercise, metabolism, scaling, crustacean, blue crab, Callinectes sapidus, phosphagen, arginine phosphate, mitochondria
This article has been cited by other articles:
|
|
 |
|
  S. T. Kinsey, K. M. Hardy, and B. R. Locke The long and winding road: influences of intracellular metabolite diffusion on cellular organization and metabolism in skeletal muscle J. Exp. Biol., October 15, 2007; 210(20): 3505 - 3512. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. C. Nyack, B. R. Locke, A. Valencia, R. M. Dillaman, and S. T. Kinsey Scaling of postcontractile phosphocreatine recovery in fish white muscle: effect of intracellular diffusion Am J Physiol Regulatory Integrative Comp Physiol, May 1, 2007; 292(5): R2077 - R2088. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. M. Hardy, B. R. Locke, M. Da Silva, and S. T. Kinsey A reaction-diffusion analysis of energetics in large muscle fibers secondarily evolved for aerobic locomotor function J. Exp. Biol., September 15, 2006; 209(18): 3610 - 3620. [Abstract] [Full Text] [PDF]
|
|
