The thermal dependence of locomotor performance and muscle contractile function in the salamander Ambystoma tigrinum nebulosum.

The thermal dependence of locomotor performance and in vitro muscle mechanical properties were studied after acclimation at 10 degrees and 20 degrees C in the salamander Ambystoma tigrinum nebulosum Hallowell. Performance measurements included burst and endurance capacities on land and in water. No significant differences in locomotor performance or muscle contractile properties were found between acclimation groups. Locomotor performance had only a slight thermal dependence, with Q10 values of 0.99-1.36 for running and swimming burst capacities (i.e. maximum speed and leg/tail cycling frequency). Running and swimming endurance capacities had thermal ratios of 1.58-1.66. Thermal dependence of muscle contractile rates was higher than that of locomotor performance: rates of force development for both isometric twitch and tetanus and maximal shortening velocity had Q10 values of 1.89-2.01. Maximal power output was also thermally dependent (Q10 = 2.33) and occurred at 38% of maximal (tetanic) force output. Force-generating capacities in isometric twitch and tetanus were relatively temperature-independent.