Differential effects of temperature on contractile behavior in isolated frog skeletal muscle

1. The thermal dependence of contractile behavior at different stimulation frequencies was investigated in isolated frog sartorius muscles. 2. Increasing incubation temperature (10-30 degrees C) produced decreases in Pt (43.7%) and P15 (70.3%), and an increase in Po (26.0%). 3. Thermal ratios (R10) calculated for Pt, P15 and Po indicated high thermal dependence at lower temperatures (10-20 degrees C; 0.60, 0.44 and 1.38, respectively) but relative thermal independence at higher temperatures (20-30 degrees C; 0.95, 0.75 and 0.95, respectively). 4. Contractile ratios (Pt/Po and P15/Po) decreased with increased temperature (10-30 degrees C; 56.3% and 76.0%, respectively). 5. Thermal ratios (R20) calculated for peak tension at different stimulation frequencies demonstrated high thermal dependence at the lower frequencies (10-30 pps, 0.46-0.48) and decreasing dependence at higher frequencies (40-50 pps, 0.69-0.82).