Effects of temperature on the locomotor performance and contraction properties of skeletal muscle from two Phrynocephalus lizards at high and low altitude

In this study, which compares P. erythrurus with  the lowlandPhrynocephalus przewalskii, we evaluated the locomotor performance at different body temperatures, the effects of temperature and oxygen partial pressure (PO2) on the contractile properties of iliofibularis (IF) muscle in vitro, ATPase activity of IF muscle at different temperatures, and the fiber types of IF muscle. LowlandP. przewalskii runs significantly faster than highlandP. erythrurus at all test body temperatures. Almost all contractile properties of the IF muscle ofP. przewalskii were better than that ofP. erythrurus under all test temperatures and PO2. However,P. erythrurus could achieve both optimal isometric (e.g., dPo/dt) and optimal isotonic (e.g.,Vmax) contraction at a lower temperature compared withP. przewalskii. Multi-factor analysis further revealed that temperature has a significant effect on the contractile properties of IF muscle for both species. Although the proportion of fibers types and ATPase activities of IF muscle have no significant interspecies difference, the changing pattern of ATPase activities with temperature is consistent with certain contractile properties and locomotor performance. The interspecies differences in locomotor ability and contractile properties of skeletal muscle in high- and low-altitude lizards may be the results of long-term adaptation to  the local environment.
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - Category: Physiology Source Type: research