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Comparison of simulated and measured calcium sparks in intact skeletal muscle fibers of the frog


, : Comparison of simulated and measured calcium sparks in intact skeletal muscle fibers of the frog. Journal of General Physiology 120(3): 349-368

Calcium sparks in frog intact skeletal muscle fibers were modeled as stereotypical events that arise from a constant efflux of Ca(2+) from a point source for a fixed period of time (e.g., 2.5 pA of Ca(2+) current for 4.6 ms; 18 degrees C). The model calculates the local changes in the concentrations of free Ca(2+) and of Ca(2+) bound to the major intrinsic myoplasmic Ca(2+) buffers (troponin, ATP, parvalbumin, and the SR Ca(2+) pump) and to the Ca(2+) indicator (fluo-3). A distinctive feature of the model is the inclusion of a binding reaction between fluo-3 and myoplasmic proteins, a process that strongly affects fluo-3's Ca(2+)-reaction kinetics, its apparent diffusion constant, and hence the morphology of sparks. DeltaF/F (the change in fluo-3's fluorescence divided by its resting fluorescence) was estimated from the calculated changes in fluo-3 convolved with the microscope point-spread function. To facilitate comparisons with measured sparks, noise and other sources of variability were included in a random repetitive fashion to generate a large number of simulated sparks that could be analyzed in the same way as the measured sparks. In the initial simulations, the binding of Ca(2+) to the two regulatory sites on troponin was assumed to follow identical and independent binding reactions. These simulations failed to accurately predict the falling phase of the measured sparks. A second set of simulations, which incorporated the idea of positive cooperativity in the binding of Ca(2+) to troponin, produced reasonable agreement with the measurements. Under the assumption that the single channel Ca(2+) current of a ryanodine receptor (RYR) is 0.5-2 pA, the results suggest that 1-5 active RYRs generate an average Ca(2+) spark in a frog intact muscle fiber.

US$19.90

PMID: 12198091

DOI: 10.1085/jgp.20028620


Other references

Marques Giraut, L., 1961: Prolapse of the uterus and pregnancy. Acta Gynaecologica et Obstetrica Hispano-Lusitana 10: 241-251

Johnson L.A.; Deyoe C.W.; Hoover W.J., 1981: Yield and quality of soy milk processed by steam infusion cooking. Traditional soymilk is boiled for approximately 60 min at 99.degree. C, pH 6.7, which reduces trypsin inhibitor (TI) activity by more than 90% to improve nutritional value. Continuous, direct steam-infusion cooking that facilitated higher temperat...

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Singh, R.; Akhtar, M.; Biswas, S.; Yadava, R., 1978: A combined therapy of tonophosphan and prepalin forte in anoestrus heifers. Indian veterinary journal: 55 (2) 157-160

Martín; Ruiz, 1985: Stationary axisymmetric post-Minkowskian metrics. Physical Review. D, Particles and Fields 32(10): 2550-2556

Voudoukis, I.J.; Caldwell, J.R., 1965: Exaggerated Natriuresis During Salt Loading In Hypertensive States. American Heart Journal 69: 570-571

Abu-Amero, K.K.; Alzahrani, A.S.; Zou, M.; Shi, Y., 2004: High frequency of somatic mitochondrial DNA mutations in human thyroid carcinomas and complex I respiratory defect in thyroid cancer cell lines. Significant progress has been made to elucidate the molecular mechanisms that determine thyroid tumor development and progression. However, most investigations have mainly focused on the genetic alterations of nuclear DNA. The potential role of mi...

Burton; Gaillard; Jain, 1990: Effective one-loop scalar Lagrangian in no-scale supergravity models. Physical Review. D, Particles and Fields 41(10): 3118-3148

Hureau J.C., 1970: Notes on the congiopodidae family telosteins perciformes rediscovery of zanclorhynchus spinifer in the kerguelen islands and re establishment of congiopodus kieneri. Bulletin Du Museum National D'Histoire Naturelle: 1019-1026

Soto-Martinez, M.; Sly, P.D., 2010: Relationship between environmental exposures in children and adult lung disease: the case for outdoor exposures. There is a growing understanding that chronic respiratory diseases in adults have their origins in early life. Adverse environmental exposures occurring in vulnerable periods during lung growth and development in the fetal period and in early chil...