Role of actomyosin in contraction of unstriated muscle
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Summary and Conclusions
Experiments have been performed on dying muscles. In such muscles, the excitatory system is destroyed and the substances act directly upon the contractile mechanism. The excitatory system was also rendered inoperative by chloroform.
In such muscles 0·1–0·3M KC1 produces contraction, and higher concentrations (0·4 to2 M) produce passive relaxation. This suggests that contraction is due to association and relaxation to dissociation of actomyosin.
Urea and thiourea produce active relaxation. As urea is also known to produce dissociation of actomyosin, these experiments suggest that the dissociation of actomyosin is of two kinds, one producing active and the other passive relaxation.
Many salts which produce dissociation of actomyosin produce relaxation.
Distilled water causes active relaxation.
The effect of potassium chloride has been tested on livingMytilus muscle in normal physiological condition. These experiments also suggest that contraction is due to association and relaxation to dissociation of actomyosin.
KeywordsPotassium Chloride Sodium Pyrophosphate Active Relaxation Excitatory System Maximal Relaxation
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