Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA.
J Exp Biol. 2012 Jan 15;215(Pt 2):256-63. doi: 10.1242/jeb.059774.
River otters (Lontra canadensis) are highly active, semi-aquatic mammals indigenous to a range of elevations and represent an appropriate model for assessing the physiological responses to diving at altitude. In this study, we performed blood gas analyses and compared blood chemistry of river otters from a high-elevation (2357 m) population at Yellowstone Lake with a sea-level population along the Pacific coast. Comparisons of oxygen dissociation curves (ODC) revealed no significant difference in hemoglobin-oxygen (Hb-O(2)) binding affinity between the two populations - potentially because of demands for tissue oxygenation. Instead, high-elevation otters had greater Hb concentrations (18.7 g dl(-1)) than sea-level otters (15.6 g dl(-1)). Yellowstone otters displayed higher levels of the vasodilator nitric oxide (NO), and half the concentration of the serum protein albumin, possibly to compensate for increased blood viscosity. Despite compensation in several hematological and serological parameters, theoretical aerobic dive limits (ADL) were similar between high-elevation and sea-level otters because of the lower availability of O(2) at altitude. Our results suggest that recent disruptions to the Yellowstone Lake food web could be detrimental to otters because at this high elevation, constraints on diving may limit their ability to switch to prey in a deep-water environment.
河狸（Lontra canadensis）是高度活跃的半水生哺乳动物，分布于多个海拔高度，是评估在高海拔潜水时生理反应的理想模型。在这项研究中，我们进行了血液气体分析，并比较了黄石湖高海拔（2357 米）种群和太平洋沿岸海平面种群的河狸血液化学特性。氧解离曲线（ODC）的比较显示，两个种群的血红蛋白-氧（Hb-O2）结合亲和力没有显著差异-这可能是由于组织氧合的需求。相反，高海拔河狸的血红蛋白浓度（18.7 g dl(-1))高于海平面河狸（15.6 g dl(-1))。黄石河狸的血管扩张剂一氧化氮（NO）水平较高，血清蛋白白蛋白的浓度减半，可能是为了补偿血液粘度的增加。尽管在几个血液学和血清学参数上有代偿作用，但由于高海拔地区氧气可用性较低，高海拔和海平面河狸的理论有氧潜水极限（ADL）相似。我们的研究结果表明，黄石湖食物网的最近破坏可能对河狸不利，因为在如此高的海拔，潜水的限制可能限制了它们在深水环境中切换到猎物的能力。
