Carnosine (α-alanyl-l-histidine), a dipeptide, the exact functions of which are unknown, is found at millimolar concentrations in muscle cells. In skinned skeletal muscle fibers, carnosine released calcium from the sarcoplasmic reticulum and generated tension, and carnosine (ED50 = 6.6 mM) was less potent than caffeine (ED50 = 1.5 mM). The effect of carnosine on the ryanodine receptor calcium release channel (Ry1) was investigated in single Ryl molecules incorporated into an artificial lipid bilayer for recording channel activity. Carnosine (0.1-10 mM) increased open-state probability (Po) of Ry1 with a fourfold maximal increase occurring at 2.5 mM. Carnosine (5 mM) caused a twofold increase in the open-state dwell time. Carnosine also altered the Ry1 channel’s response to changes in calcium concentration, shifting the Po-versus-pCa relationship to the left. The presence of carnosine at a millimolar concentration in muscle cells and its effects on the major calcium release channel in skeletal muscle suggest an important function for this unique dipeptide in regulation of contractility. One possible function of carnosine is the sensitization of key proteins to activation and/or inactivation by Ca2+.

Journal Section:
Original Paper
Keywords:
Calcium channels, Carnosine, Peptide, Skeletal muscle contractility
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© 1997 S. Karger AG, Basel
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1997
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