[Concentration and rate of depletion of glycogen in fast and slow rat muscles].

Glycogen content of the fast m. tibialis anterior at rest is higher than in the slow m. soleus: 0.650 +/- 0.030 and 0.540 +/- 0.029 g/100 muscle wet weight, resp. A considerable glycogen breakdown occurs in both muscles in alternative regimen of 5-sec tetanic contraction and 5-sec rest. The rate of depletion is maximal during the first 10-min contraction, then it slows down abruptly to an approximately constant level during the further 30-min contaction. Linear correlation exists between the rate of glycogen depletion and glycogen content at rest, the correlation being especially high in the m. tibialis anterior. The rate of correlation increases with prolongation of stimulation in both muscles. The degree of glycogen depletion and the depletion rate are higher in the m. tibialis anterior than in the m. soleus. The relation is independent of glycogen content in the muscles at rest.