Xin Ying, Wang Yan, Wang Huihui, Tang Xiaolong, Bai Yucheng, Lu Songsong, Xin Ying
Medical College of Northwest Minzu University, Lanzhou, China.
School of Public Health and Management, Ningxia Medical University, Yinchuan, China.
Comp Biochem Physiol B Biochem Mol Biol. 2019 Apr;230:29-36. doi: 10.1016/j.cbpb.2019.01.009. Epub 2019 Jan 25.
Nitric oxide (NO), produced by nitric oxide synthases (NOS) from L-arginine, plays important roles in a wide range of physiological processes. However, little is known about ectothermic species. To investigate the response of NO/NOS system in adaptation to different altitudes in Phrynocephalus genus, the red tail toad-headed lizard Phrynocephalus erythrurus that live at 4500-5300 m on the Qinghai-Tibet Plateau and another low altitude living lizard Phrynocephalus przewalskii were selected in the present study. The results of mRNA expression and activity of NOSs, as well as NO metabolite levels in different tissues of the two lizards indicate that nNOS mRNA levels in cardiac and skeletal muscle were notably elevated in P. erythrurus, and iNOS expression was also increased markedly (up to 4-fold) in cardiac muscle. There was no significant difference in eNOS mRNA level in tested tissues between two species. However, the total NOS activity in skeletal muscle of P. erythrurus was slightly lower than that of P. przewalskii (p < .05) while no difference in other tissues. Similarly, lower iNOS activity (p < .01) was found in cardiac and skeletal muscle in P. erythrurus compared to P. przewalskii. In addition, the NO metabolite levels were dramatically lower in P. erythrurus in all tested tissues. We propose that higher nNOS and iNOS mRNA expression, lower iNOS activity and NO metabolite levels may represent physiological characteristics in nitric oxide system, which may contribute to high-altitude adaptation in P. erythrurus.
一氧化氮合酶（NOS）利用L-精氨酸产生的一氧化氮（NO）在广泛的生理过程中发挥着重要作用。然而，对于变温动物物种却知之甚少。为了研究NO/NOS系统在沙蜥属适应不同海拔过程中的反应，本研究选取了生活在青藏高原4500 - 5300米处的红尾沙蜥（Phrynocephalus erythrurus）以及另一种生活在低海拔地区的蜥蜴青海沙蜥（Phrynocephalus przewalskii）。两种蜥蜴不同组织中NOS的mRNA表达、活性以及NO代谢物水平的结果表明，红尾沙蜥心脏和骨骼肌中的nNOS mRNA水平显著升高，并且心肌中的iNOS表达也显著增加（高达4倍）。两个物种测试组织中的eNOS mRNA水平没有显著差异。然而，红尾沙蜥骨骼肌中的总NOS活性略低于青海沙蜥（p < 0.05），而其他组织中没有差异。同样，与青海沙蜥相比，红尾沙蜥心脏和骨骼肌中的iNOS活性较低（p < 0.01）。此外，红尾沙蜥所有测试组织中的NO代谢物水平都显著较低。我们认为，较高的nNOS和iNOS mRNA表达、较低的iNOS活性和NO代谢物水平可能代表了一氧化氮系统的生理特征，这可能有助于红尾沙蜥适应高海拔环境。
