Effect of aminophylline on muscle fatigue.

The effects of two different concentrations of aminophylline, 50 microM/L and 500 microM/L on muscle fatiguability were tested using frog gastrocnemius-sciatic preparations. Two stimulation protocols, one high energy demand, and the other low energy demand were used to induce muscle fatigue. The indices of fatigue employed were (a) the decrease in peak tetanic contraction, (b) the increase in half-contraction time and (c) the increase in the contraction period in response to a high-energy-demand stimulation protocol of fatigue-induction. At the same time, it prolongs the increase in relaxation50-80 time in response to the same protocol.