Calcium sensitizing action of carnosine and other endogenous imidazoles in chemically skinned striated muscle.
1. The imidazole-containing compounds carnosine and homocarnosine, endogenous to skeletal and cardiac muscle, have been tested for effect on the contractile behaviour of chemically skinned (saponin or Triton X-100) skeletal and cardiac muscle. 2. Carnosine, at millimolar concentrations which are near physiological for many skeletal fibres, and in a concentration-dependent fashion, shifts the curve relating [Ca2+] to steady-state tension to lower [Ca2+] in both skeletal (frog but not crab) and cardiac (rat) muscle preparations. 3. Of other imidazoles endogenous to heart, homocarnosine is somewhat more effective, while N-acetyl L-histidine is much less so. 4. The maximum level of Ca(2+)-activated force is increased significantly by homocarnosine in cardiac trabeculae. 5. We propose that the cellular imidazoles related to carnosine are natural 'Ca2+ sensitizers' in striated muscle. Alterations in their levels as a result of disease or training, and between different fibre types, may contribute to differences in contractile performance of the intact tissues.
Lamont
C
C
Institute of Physiology, The University, Glasgow.
Miller
D J
DJ
D000818:Animals; D003386:Brachyura; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002336:Carnosine / Q000494:pharmacology*; D006321:Heart / Q000502:physiology; D006639:Histidine / Q000031:analogs & derivatives / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology*; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects* / Q000502:physiology; D009132:Muscles / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D009200:Myocardial Contraction / Q000187:drug effects* / Q000502:physiology; D011896:Rana temporaria; D051381:Rats; D014982:Xenopus laevis
D007093:Imidazoles; D002110:Caffeine; D006639:Histidine; D002336:Carnosine; C023495:N-acetylhistidine; D002118:Calcium