Data from: Adenosine receptors mediate the hypoxic ventilatory response but not the hypoxic metabolic response in the naked mole rat during acute hypoxia

Naked mole rats are the most hypoxia-tolerant mammals identified; however, the mechanisms underlying this tolerance are poorly understood. Using whole-animal plethysmography and open-flow respirometry we examined the hypoxic metabolic response (HMR), hypoxic ventilatory response (HVR), and hypoxic thermal response in awake, freely-behaving naked mole rats exposed to 7% O2 for 1 hr. Metabolic rate and ventilation each reversibly decreased 70% in hypoxia (from 39.6 ± 2.9 to 12.1 ± 0.3 ml O2•min-1•kg-1, and 1412 ± 244 to 417 ± 62 ml•min-1•kg-1, respectively; p < 0.05), whereas body temperature was unchanged and animals remained awake and active. Subcutaneous injection of the general adenosine receptor antagonist aminophylline (AMP; 100 mg•kg-1, in saline), but not control saline injections, prevented the HVR but had no effect on the HMR. As a result, AMP-treated naked mole rats exhibited extreme hyperventilation in hypoxia. These animals were also less tolerant to hypoxia, and in some cases hypoxia was lethal following AMP injection. We conclude that in naked mole rats: 1) hypoxia-tolerance is partially dependent on profound hypoxic metabolic and ventilatory responses, which are equal in magnitude but occur independently of thermal changes in hypoxia, and 2) adenosine receptors mediate the HVR but not the HMR.裸鼹鼠（naked mole rats）是目前已发现的耐低氧能力最强的哺乳动物，但学界对其介导该耐受性的潜在机制尚不清楚。本研究采用整体体积描记法（whole-animal plethysmography）与开放式呼吸测热法（open-flow respirometry），对暴露于7%氧气环境中1小时的清醒自由活动裸鼹鼠的低氧代谢反应（hypoxic metabolic response, HMR）、低氧通气反应（hypoxic ventilatory response, HVR）及低氧体温反应进行了检测。低氧环境下，受试动物的代谢率与通气量均出现70%的可逆性下降（分别从39.6 ± 2.9 ml O₂·min⁻¹·kg⁻¹降至12.1 ± 0.3 ml O₂·min⁻¹·kg⁻¹，以及从1412 ± 244 ml·min⁻¹·kg⁻¹降至417 ± 62 ml·min⁻¹·kg⁻¹；p < 0.05），但体温未发生变化，且动物始终保持清醒与活跃状态。皮下注射广谱腺苷受体拮抗剂氨茶碱（aminophylline, AMP；100 mg·kg⁻¹，溶于生理盐水）可阻断低氧通气反应，而单纯注射生理盐水的对照组则无此阻断效应，且氨茶碱注射对低氧代谢反应无显著影响。据此，接受氨茶碱注射的裸鼹鼠在低氧环境下出现了严重的过度通气现象。此类动物的低氧耐受性也有所降低，部分个体在注射氨茶碱后甚至出现了低氧致死情况。本研究得出如下结论：其一，裸鼹鼠的低氧耐受性部分依赖于显著的低氧代谢与通气反应——二者幅度相当，但独立于低氧环境下的体温变化而发生；其二，腺苷受体介导了低氧通气反应，但并未参与低氧代谢反应。