Regulation analysis of contractile ATPase flux in skeletal muscle.
J The [Ca2+] regulation of contractile ATPase flux, Jp, in skeletal muscle was analysed by computation of the Response R(Jp) Ca2+ for a 10 Hz range of electrical stimulation frequencies. Results of our analysis of the kinetic controls in ATP free energy metabolism in a network model of contracting muscle (J.A.L. Jeneson, H.V. Westerhoff and M.J. Kushmerick (2000) Am. J Physiol. 279, C813-C832) formed the basis for the computations of R(Jp) Ca2+. We found that neural regulation of sustained force generation via simple [Ca2+]cyto frequency encoding in the network was robust for frequencies up to 2 Hz. Above 2 Hz, however, this regulation design broke down because of a shift in contractile ATPase flux control from the Ca2+-sensitive contractile filaments to mitochondria with low Ca2+ sensitivity. The role of glyco(geno)lytic ATP production at high contraction workloads is discussed in the context of this result.
Jeneson
J A L
JA
Department of Physiology, School of Veterinary Medicine, Utrecht University, NL.
D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D004558:Electric Stimulation; D006801:Humans; D008433:Mathematics; D008931:Mitochondria, Muscle / Q000201:enzymology; D008954:Models, Biological; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism*; D013816:Thermodynamics
D009218:Myosins; D000252:Calcium-Transporting ATPases; D002118:Calcium