Dzal Yvonne A, Seow Allison, Borecky Lisa G, Chung Danielle, Gill Sharn K G, Milsom William K, Pamenter Matthew E
Department of Zoology, University of British Columbia, Vancouver, BC, Canada.
Department of Biology, Centre for Forest Interdisciplinary Research, University of Winnipeg, Winnipeg, MB, Canada.
Front Physiol. 2019 Feb 18;10:106. doi: 10.3389/fphys.2019.00106. eCollection 2019.
Naked mole rats () are among the most hypoxia-tolerant mammals, but their physiological responses to acute and chronic sustained hypoxia (CSH), and the molecular underpinnings of these responses, are poorly understood. In the present study we evaluated the acute hypoxic ventilatory response and the occurrence of ventilatory acclimatization to hypoxia following CSH exposure (8-10 days in 8% O) of naked mole rats. We also investigated the role of excitatory glutamatergic signaling in the control of ventilation and metabolism in these conditions. Animals acclimated to normoxia (control) or CSH and then exposed to acute hypoxia (7% O for 1 h) exhibited elevated tidal volume (V), but decreased breathing frequency (f). As a result, total ventilation ( ) remained unchanged. Conversely, V was lower in CSH animals relative to controls, suggesting that there is ventilatory plasticity following acclimatization to chronic hypoxia. Both control and CSH-acclimated naked mole rats exhibited similar 60-65% decreases in O consumption rate during acute hypoxia, and as a result their air convection requirement (ACR) increased ∼2.4 to 3-fold. Glutamatergic receptor inhibition decreased f, , and the rate of O consumption in normoxia but did not alter these ventilatory or metabolic responses to acute hypoxia in either the control or CSH groups. Taken together, these findings indicate that ventilatory acclimatization to hypoxia is atypical in naked mole rats, and glutamatergic signaling is not involved in their hypoxic ventilatory or metabolic responses to acute or chronic hypoxia.
裸鼹鼠是最耐缺氧的哺乳动物之一，但它们对急性和慢性持续性缺氧（CSH）的生理反应以及这些反应的分子基础却知之甚少。在本研究中，我们评估了裸鼹鼠的急性缺氧通气反应以及在暴露于CSH（8%氧气环境下8 - 10天）后对缺氧的通气适应情况。我们还研究了兴奋性谷氨酸能信号在这些条件下对通气和代谢控制中的作用。适应常氧（对照）或CSH的动物，然后暴露于急性缺氧（7%氧气，1小时）时，潮气量（V）升高，但呼吸频率（f）降低。结果，总通气量（ ）保持不变。相反，与对照组相比，CSH组动物的V较低，这表明在适应慢性缺氧后存在通气可塑性。对照和CSH适应的裸鼹鼠在急性缺氧期间耗氧率均下降了60 - 65%，因此它们的空气对流需求（ACR）增加了约2.4至3倍。谷氨酸能受体抑制降低了常氧下的f、 和耗氧率，但在对照组或CSH组中均未改变对急性缺氧的这些通气或代谢反应。综上所述，这些发现表明裸鼹鼠对缺氧的通气适应是非典型的，并且谷氨酸能信号不参与它们对急性或慢性缺氧的缺氧通气或代谢反应。
