[Effect of physical exercise on myoglobin and tropomyosin levels in skeletal muscles and myoglobin level in rat blood].

Single intensive physical exercise caused phase alterations in content of myoglobin and tropomyosin in rat skeletal muscles. Within the first 2-4 hrs of rest concentration of myoglobin and tropomyosin was decreased in muscles by 40-50% (catabolic, urgent step of adaptation). Within the later period of rest (72-120 hrs) content of myoglobin and tropomyosin was increased by 25-30% (anabolic, later step of adaptation) as compared with the control level. Similar phase alterations of these proteins in skeletal muscles were detected in trained animals but they were less distinct. Training of the animals led to elevation in content of the proteins in musculus quadriceps. The content of myoglobin increased from 1.2 +/- 0.1 mg/kg up to 2.6 +/- 0.1 mg/kg and that of tropomyosin from 4.9 +/- 0.1 mg/kg up to 5.5 +/- 0.1 mg/kg as a result of an increase in protein biosynthesis. Incorporation of 14C-leucine into myoglobin was increased 1.7-fold. Concentration of myoglobin in blood of untrained rats was increased 3-fold immediately after physical exercises and--9-fold within 72 hrs of the rest. Content of muscular proteins in blood reflected the response of muscle system to physical exercises and may serve as a criterion in evaluation of various steps of adaptation to physical loading.