Acute effects of taurine on sarcoplasmic reticulum Ca^sup 2+^ accumulation and contractility in human type I and type II skeletal muscle fibers

Taurine occurs in high concentrations in muscle and is implicated in numerous physiological processes, yet its effects on many aspects of contractility remain unclear. Using mechanically skinned segments of human vastus lateralis muscle fibers, we characterized the effects of taurine on sarcoplasmic...

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Bibliographic Details
Published in:Journal of applied physiology (1985) 2014-10, Vol.117 (7), p.797
Main Authors: Dutka, T L, Lamboley, C R, Murphy, R M, Lamb, G D
Format: Article
Language:English
Subjects:
Amino acids
Calcium
Cytoplasm
Musculoskeletal system
Physiology
Online Access:Get full text
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Summary:Taurine occurs in high concentrations in muscle and is implicated in numerous physiological processes, yet its effects on many aspects of contractility remain unclear. Using mechanically skinned segments of human vastus lateralis muscle fibers, we characterized the effects of taurine on sarcoplasmic reticulum (SR) Ca... accumulation and contractile apparatus properties in type I and type II fibers. Prolonged myoplasmic exposure (>10 min) to taurine substantially increased the rate of accumulation of Ca... by the SR in both fiber types, with no change in the maximum amount accumulated; no such effect was found with carnosine. SR Ca... accumulation was similar with 10 or 20 mM taurine, but was significantly slower at 5 mM taurine. Cytoplasmic taurine (20 mM) had no detectable effects on the responsiveness of the Ca... release channels in either fiber type. Taurine caused a small increase in Ca... sensitivity of the contractile apparatus in type I fibers, but type II fibers were unaffected; maximum Ca...-activated force was unchanged in both cases. The effects of taurine on SR Ca... accumulation 1) only became apparent after prolonged cytoplasmic exposure, and 2) persisted for some minutes after complete removal of taurine from the cytoplasm, consistent with the hypothesis that the effects were due to an action of taurine from inside the SR. In summary, taurine potentiates the rate of SR Ca... uptake in both type I and type II human fibers, possibly via an action from within the SR lumen, with the degree of potentiation being significantly reduced at low physiological taurine levels. (ProQuest: ... denotes formulae/symbols omitted.)
ISSN:8750-7587
1522-1601