Effect of carnosine on excitation-contraction coupling in mechanically-skinned rat skeletal muscle

This study investigated whether carnosine alters individual processes involved in normal excitation-contraction (E-C) coupling in mammalian skeletal muscle fibres. Mechanically-skinned fibre preparations were utilized because they allow carnosine to be precisely and readily applied to the cytoplasmi...

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Bibliographic Details
Published in:Journal of muscle research and cell motility 2004-01, Vol.25 (3), p.203-213
Main Authors: Dutka, Travis L, Lamb, Graham D
Format: Article
Language:English
Subjects:
Animals
Carnosine - pharmacology
Dose-Response Relationship, Drug
In Vitro Techniques
Muscle Contraction - drug effects
Muscle Contraction - physiology
Muscle, Skeletal - drug effects
Muscle, Skeletal - physiology
Muscular system
Proteins
Rats
Rats, Long-Evans
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Summary:This study investigated whether carnosine alters individual processes involved in normal excitation-contraction (E-C) coupling in mammalian skeletal muscle fibres. Mechanically-skinned fibre preparations were utilized because they allow carnosine to be precisely and readily applied to the cytoplasmic environment as desired, whilst still retaining the normal E-C coupling mechanism. Carnosine caused an increase (approximately +0.02 to approximately +0.09 pCa units) in Ca2+ -sensitivity of the contractile apparatus in a concentration-dependent manner (i.e. with 4, 8 and 16 mM respectively). Force responses elicited by 8 mM caffeine-induced Ca2+ release from the sarcoplasmic reticulum (SR) were potentiated in the presence of carnosine (compared to the bracketing responses in the absence of carnosine). Force responses elicited by transverse tubular (T-) system depolarization via the dihydropyridine receptors (DHPRs), either by ionic (Na+) substitution or by action potentials (APs), were also potentiated in a concentration-dependent manner in the presence of carnosine. The potentiation of the force responses in all of the various experiments was seemingly totally explicable by the increase in Ca2+-sensitivity of the contractile apparatus caused by carnosine. Thus, these results show that carnosine potentiates force responses solely by 'sensitizing' the contractile apparatus to Ca2+ ions and under physiological conditions does not cause additional Ca2+ release from the SR.
ISSN:0142-4319
1573-2657
DOI:10.1023/B:JURE.0000038265.37022.c5