[Changes in carnosine levels in muscles working in different regimens of stimulation]

Carnosine content in muscles functioning under single or tetanic (both direct and indirect) contractions, in the period of active contractility (within the first 10 min of experiment) and in fatigued muscles was determined. In exercising muscle, carnosine content was shown to decrease. The loss of the dipeptide during active contractions was, on the average, 10.5%; that at fatigue--13.8%. At exercise (single contractions), the decrease of carnosine was higher than in the muscles functioning in a short tetanus regime. It was shown that the previously described phenomenon of fatigue elimination by carnosine addition to the Ringer solution washing the muscle is concomitant with the elevation (by 12%) of the intramuscular concentration of exogenous carnosine.