Department of Animal and Biomedical Sciences, School of Life Science, Lanzhou University, No. 222 Tianshui South Road, Lanzhou, 730000, Gansu, China.
School of Stomatologymatology, Lanzhou University, No. 199 Donggang West Road, Lanzhou, 730000, Gansu, China.
J Comp Physiol B. 2021 Sep;191(5):907-916. doi: 10.1007/s00360-021-01391-9. Epub 2021 Aug 3.
Locomotor performance and skeletal muscle contraction are critical for animals and are susceptible to changes in the external thermal environment, especially for ectotherms. Phrynocephalus erythrurus, which is endemic to the Qinghai-Tibetan plateau, is known for living at the highest elevation among all reptiles in the world (4500-5300 m). In this study, which compares P. erythrurus with the lowland Phrynocephalus przewalskii, we evaluated the locomotor performance at different body temperatures, the effects of temperature and oxygen partial pressure (PO) 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. Lowland P. przewalskii runs significantly faster than highland P. erythrurus at all test body temperatures. Almost all contractile properties of the IF muscle of P. przewalskii were better than that of P. erythrurus under all test temperatures and PO. However, P. erythrurus could achieve both optimal isometric (e.g., dP/dt) and optimal isotonic (e.g., V) contraction at a lower temperature compared with P. 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.
运动表现和骨骼肌收缩对于动物至关重要，易受外部热环境变化的影响，尤其是变温动物。变色沙蜥是青藏高原特有的物种，是世界上所有爬行动物中生活海拔最高的物种（4500-5300 米）。在这项比较变色沙蜥和低海拔的青海沙蜥的研究中，我们评估了不同体温下的运动表现，温度和氧分压（PO）对离体髂肋肌（IF）肌肉收缩特性的影响，不同温度下 IF 肌肉的 ATP 酶活性，以及 IF 肌肉的纤维类型。低海拔的青海沙蜥在所有测试体温下的奔跑速度都明显快于高海拔的变色沙蜥。在所有测试温度和 PO 下，IF 肌肉的几乎所有收缩特性都优于变色沙蜥。然而，与青海沙蜥相比，变色沙蜥可以在较低的温度下达到最佳等长（例如，dP/dt）和最佳等张（例如，V）收缩。多因素分析进一步表明，温度对两种蜥蜴 IF 肌肉的收缩特性有显著影响。尽管 IF 肌肉的纤维类型比例和 ATP 酶活性没有明显的种间差异，但 ATP 酶活性随温度的变化模式与某些收缩特性和运动表现一致。高海拔和低海拔蜥蜴的运动能力和骨骼肌收缩特性的种间差异可能是长期适应当地环境的结果。
