West T G, Boutilier R G
Department of Zoology, University of Cambridge, England.
J Comp Physiol B. 1998 May;168(4):273-80. doi: 10.1007/s003600050146.
Microcalorimetry is the only direct method for measuring moment-to-moment changes in whole-cell metabolism (as heat output) during anoxia. We have adapted this methodology, in conjunction with standard muscle isolation techniques, to monitor metabolic transitions in isolated frog (Rana temporaria) sartorius muscle during anoxia and recovery (reoxygenation). Anoxia (sustained 1 h, following 2 h progressive hypoxia) suppressed muscle heat output to 20% of the stable normoxic level. This effect was fully reversible upon reoxygenation. Metabolite profiles were consistent with other anoxia-tolerant vertebrates--most notably, adenosine triphosphate (ATP) content during anoxia and reoxygenation remained unchanged from normoxia (pre-anoxic control). In addition, the concentration of K+ ions ([K+]) in interstitial dialysates remained stable (2-3 mM) throughout anoxia and recovery. Interstitial [lactate-] increased slightly, in accord with anaerobiosis supporting suppressed metabolic rates during anoxia. The degree of anoxic suppression of metabolism observed is similar to other vertebrate models of anoxia tolerance. Furthermore, stable ATP concentrations and interstitial [K+] in the isolated tissue suggests that intrinsic mechanisms suppress metabolism in a manner that coordinates ATP supply and demand and avoids the severe ion imbalances that are characteristics of hypoxia-sensitive systems.
微量量热法是测量缺氧期间全细胞代谢逐时变化（作为热量输出）的唯一直接方法。我们已将这种方法与标准的肌肉分离技术相结合，以监测缺氧和恢复（复氧）期间分离的青蛙（林蛙）缝匠肌中的代谢转变。缺氧（在2小时渐进性缺氧后持续1小时）将肌肉热量输出抑制至稳定常氧水平的20%。这种效应在复氧后完全可逆。代谢物谱与其他耐缺氧脊椎动物一致——最显著的是，缺氧和复氧期间的三磷酸腺苷（ATP）含量与常氧（缺氧前对照）相比保持不变。此外，在整个缺氧和恢复过程中，间质透析液中的钾离子浓度（[K+]）保持稳定（2 - 3 mM）。间质[乳酸-]略有增加，这与无氧代谢支持缺氧期间受抑制的代谢率一致。观察到的缺氧对代谢的抑制程度与其他耐缺氧脊椎动物模型相似。此外，分离组织中稳定的ATP浓度和间质[K+]表明，内在机制以协调ATP供应和需求并避免缺氧敏感系统特有的严重离子失衡的方式抑制代谢。
