Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada
Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada.
J Exp Biol. 2021 Jan 7;224(Pt 1):jeb237024. doi: 10.1242/jeb.237024.
Hypoxia exposure can have distinct physiological effects between early developmental and adult life stages, but it is unclear how the effects of hypoxia may progress during continuous exposure throughout life. We examined this issue in deer mice () from a population native to high altitude. Mice were bred in captivity in one of three treatment groups: normoxia (controls), life-long hypoxia (∼12 kPa O from conception to adulthood) and parental hypoxia (normoxia from conception to adulthood, but parents previously exposed to hypoxia). Metabolic, thermoregulatory and ventilatory responses to progressive stepwise hypoxia and haematology were then measured at post-natal day (P) 14 and 30 and/or in adulthood. Life-long hypoxia had consistent effects across ages on metabolism, attenuating the declines in O consumption rate ( ) and body temperature during progressive hypoxia compared with control mice. However, life-long hypoxia had age-specific effects on breathing, blunting the hypoxia-induced increases in air convection requirement (quotient of total ventilation and ) at P14 and P30 only, but then shifting breathing pattern towards deeper and/or less frequent breaths at P30 and adulthood. Hypoxia exposure also increased blood-O affinity at P14 and P30, in association with an increase in arterial O saturation in hypoxia at P30. In contrast, parental hypoxia had no effects on metabolism or breathing, but it increased blood-O affinity and decreased red cell haemoglobin content at P14 (but not P30). Therefore, hypoxia exposure has some consistent effects across early life and adulthood, and some other effects that are unique to specific life stages.
缺氧暴露在早期发育和成年阶段会产生明显的生理效应，但尚不清楚在整个生命过程中持续暴露于缺氧环境下，这些效应会如何进展。我们研究了来自高海拔地区的本地鹿鼠（）的这个问题。将这些老鼠在三种处理组中的一种中进行人工饲养：常氧（对照组）、终生缺氧（从受孕到成年时保持约 12kPa 的氧分压）和母体缺氧（从受孕到成年时保持常氧，但父母之前曾暴露于缺氧环境）。然后在出生后第 14 天和第 30 天和/或成年时测量其对逐步递增的缺氧的代谢、体温调节和通气反应以及血液学指标。终生缺氧对代谢有一致的影响，与对照组相比，在逐渐缺氧过程中，耗氧量（）和体温的下降幅度减小。然而，终生缺氧对呼吸有年龄特异性影响，仅在第 14 天和第 30 天，减弱了缺氧诱导的空气对流需求（总通气量和的商）的增加，但随后在第 30 天和成年时呼吸模式转向更深和/或更不频繁的呼吸。缺氧暴露还增加了第 14 天和第 30 天的血液氧亲和力，与第 30 天的动脉血氧饱和度在缺氧时增加有关。相比之下，母体缺氧对代谢或呼吸没有影响，但它增加了第 14 天的血液氧亲和力并降低了红细胞血红蛋白含量（但第 30 天没有）。因此，缺氧暴露在整个早期生命和成年期有一些一致的影响，在特定的生命阶段还有一些其他的独特影响。
