Defense Strategies Against Hypoxia

摘要: Despite considerable capacity for performance under the hypobaric hypoxia of high altitude [31,32], man is an aerobic animal and at rest consumes 3.5 ml O2/kg per min, equivalent to about 0.17 mmol min. Under normal circumstances, well over 90% this O2 utilized by mitochondrial metabolism in formation adenosine triphosphate (ATP); steady state, ATP same rates as it produced, so consumption rate 1.02 turned kilogram minute. It has been universally recognized a century, since pioneering work Pasteur [27], that becomes limiting, anaerobic metabolic processes are activated (the effect). That is, make up energy deficit due depressed production rates. What not widely appreciated tissue dependence effect. Some cells, like those central nervous system (CNS), show large (about tenfold) activation glycolysis when limiting. Mammalian liver cells sevenfold glycolytic activation. regions kidney relatively effect (ninefold), other intermediate regard, while still others only modest doubling blocked. Perhaps extreme case mammalian body skeletal muscle, which extremely ischemic conditions sustains such low turnover can be satisfied lower flux than required normoxic resting metabolism; called reverse Similar tissue- specific differences also evident cross-species comparisons. In essentially all cases, hypoxia-tolerant tissues or species, unlike hypoxia-sensitive ones, reversed effects energetic terms means they sustain significant suppression during [12,13,16].