[Protein metabolism in the muscles after work]

The 20-hr swimming increased the contants of protein, thyrosine and 3-methylhistidine (also per 1 g of protein) in skeletal muscle of rat within 2-24 hrs. A significant increase in 3-methylhistidine excretion followed this on the 2nd day of the recovery period. The revealed combination of changes suggests a simultaneous augmentation of both synthesis and disintegration of protein in muscles after their activity. Hence, the increased excretion of 3-methylhistidine during recovery period reflects an intensive renewal of the molecular content of proteins of actinomyosine complex. The 3-methylhistidine level in intestine increased only for a short time and seems not to contribute to the delayed increase in excretion of the amino acid.