title: The sensitivity of fast muscle contractile function to the major components of the sarcomere Ca(2+)-cycling system.
abstract: A reaction-diffusion model of a muscle sarcomere was developed to evaluate the sensitivity of force characteristics to diffusion and Ca(2+)-cycling components. The model compared well to experimental force measurements. Diffusion led to Ca(2+) gradients that enhanced maximal force and accelerated relaxation compared to when diffusion was infinitely fast. However, a modest increase in sarcomere length or radius led to a decrease in maximal force. Lowering the Ca(2+) release rate caused a lower maximal force, but increasing the rate led to only modest gains in maximal force while incurring much greater ATP costs associated with reuptake. Greater parvalbumin binding rates decreased maximal force but enhanced relaxation, and this effect was magnified when Ca(2+) uptake rates were lowered as may occur during fatigue. These results show a physiological set of parameters that lead to a functional sarcomere of known dimensions and contractile function, and the effects of parameter variation on muscle function.
authors.affiliation: Department of Chemical and Biomedical Engineering, Florida State University, FAMU-FSU College of Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310, United States.
authors.forename: C
authors.initials: C
authors.lastname: Golding
authors.affiliation: Department of Biology and Marine Biology, University of North Carolina Wilmington, 601 South College Road, Wilmington, NC 28403-5915, United States.
authors.forename: K
authors.initials: K
authors.lastname: Kelly
authors.affiliation: Department of Biology and Marine Biology, University of North Carolina Wilmington, 601 South College Road, Wilmington, NC 28403-5915, United States.
authors.forename: S T
authors.initials: ST
authors.lastname: Kinsey
authors.affiliation: Department of Chemical and Biomedical Engineering, Florida State University, FAMU-FSU College of Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310, United States. Electronic address: locke@eng.fsu.edu.
authors.forename: B R
authors.initials: BR
authors.lastname: Locke
mesh_terms: D000818:Animals; D001492:Bass; D002118:Calcium / Q000378:metabolism*; D004058:Diffusion; D009119:Muscle Contraction; D010320:Parvalbumins / Q000378:metabolism; D012518:Sarcomeres / Q000378:metabolism*
chemical_list: D010320:Parvalbumins; D002118:Calcium
keywords: Calcium; Contraction; Diffusion; Sarcomere; Sarcoplasmic reticulum; Skeletal muscle