Abstract des Autors

In Wistar rats 19-h swimming induced an increased protein degradation rate in the soleus muscle that persisted for at least the first 24 h of postexercise recovery. Immediately after exercise the protein synthesis rate was on the level of sedentary controls. During the first 12 h of the recovery period it decreased. The protein synthesis rate returned to the control level 24 h after exercise and exceeded it 48 h after exercise. In m. rectus femoris contents of free tyrosine and 3-methylhistidine were increased in a period from 2 to 24 hrs after the end of swimming. This was accompanied by an augmented blood level of tyrosine and corticosterone and elevated glycogen content in liver and muscle. It was followed by augmented 3-methylhistidine excretion on the second day of the recovery period. If in the skeletal muscle the 3-methylhistidine level was augmented for a 22 hour period, then in the intestinal tissue the 3-methylhistidine level was elevated only during the first two hours after exercise. In is concluded that: (1) The recovery period is not characterized by augmented anabolism alone, but by an increased rate of protein turnover in the muscle. (2) The increased 3-methylhistidine excretion after exercise must not be considered as an index of the prevalent breakdown of contractile proteins, but as a sign of their increased turnover. (3) There is only a minor contribution of 3-methylhistidine derived from intestinal tissue to its increased excretion after exercise. Verf.-Referat