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Comprehensive Simulation of Ca2+ Transients in the Continuum of Mouse Skeletal Muscle Fiber Types
- Source :
- International Journal of Molecular Sciences, Vol 22, Iss 12378, p 12378 (2021), International Journal of Molecular Sciences, Volume 22, Issue 22
- Publication Year :
- 2021
- Publisher :
- MDPI AG, 2021.
-
Abstract
- Mag-Fluo-4 has revealed differences in the kinetics of the Ca2+ transients of mammalian fiber types (I, IIA, IIX, and IIB). We simulated the changes in [Ca2+] through the sarcomere of these four fiber types, considering classical (troponin –Tn–, parvalbumin –Pv–, adenosine triphosphate –ATP–, sarcoplasmic reticulum Ca2+ pump –SERCA–, and dye) and new (mitochondria –MITO–, Na+/Ca2+ exchanger –NCX–, and store-operated calcium entry –SOCE–) Ca2+ binding sites, during single and tetanic stimulation. We found that during a single twitch, the sarcoplasmic peak [Ca2+] for fibers type IIB and IIX was around 16 µM, and for fibers type I and IIA reached 10–13 µM. The release rate in fibers type I, IIA, IIX, and IIB was 64.8, 153.6, 238.8, and 244.5 µM ms−1, respectively. Both the pattern of change and the peak concentrations of the Ca2+-bound species in the sarcoplasm (Tn, PV, ATP, and dye), the sarcolemma (NCX, SOCE), and the SR (SERCA) showed the order IIB ≥ IIX &gt<br />IIA &gt<br />I. The capacity of the NCX was 2.5, 1.3, 0.9, and 0.8% of the capacity of SERCA, for fibers type I, IIA, IIX, and IIB, respectively. MITO peak [Ca2+] ranged from 0.93 to 0.23 µM, in fibers type I and IIB, respectively, while intermediate values were obtained in fibers IIA and IIX. The latter numbers doubled during tetanic stimulation. In conclusion, we presented a comprehensive mathematical model of the excitation–contraction coupling that integrated most classical and novel Ca2+ handling mechanisms, overcoming the limitations of the fast- vs. slow-fibers dichotomy and the use of slow dyes.
- Subjects :
- SERCA
QH301-705.5
Sarcoplasm
tetanus
Sarcomere
Catalysis
Inorganic Chemistry
medicine
Myocyte
ECC
Physical and Theoretical Chemistry
Biology (General)
Molecular Biology
QD1-999
Spectroscopy
Sarcolemma
Chemistry
Endoplasmic reticulum
Organic Chemistry
Skeletal muscle
muscle cells
General Medicine
Ca2+ dyes
musculoskeletal system
mathematical simulation
Computer Science Applications
medicine.anatomical_structure
Biophysics
Tetanic stimulation
Subjects
Details
- Language :
- English
- ISSN :
- 16616596 and 14220067
- Volume :
- 22
- Issue :
- 12378
- Database :
- OpenAIRE
- Journal :
- International Journal of Molecular Sciences
- Accession number :
- edsair.doi.dedup.....b45f9e63f2ad11b29678f4dffbb68621