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

Abstract

1. 1. The thermal dependence of contractile behavior at different stimulation frequencies was investigated in isolated frog sartorius muscles. 2. 2. Increasing incubation temperature (10–30°C) produced decreases in P t, (43.7%) and P 15 (70.3%), and an increase in P o (26.0%). 3. 3. Thermal ratios ( R 10) calculated for P t, P 15 and P o indicated high thermal dependence at lower temperatures (10–20°C; 0.60, 0.44 and 1.38, respectively) but relative thermal independence at higher temperatures (20–30°C; 0.95, 0.75 and 0.95, respectively). 4. 4. Contractile ratios ( P t P o and P 15 P o ) decreased with increased temperature (10–30°C; 56.3% a 76.0%, respectively). 5. 5. Thermal ratios ( R 20) 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).