The role of oxygen in metabolic regulation

摘要: 1. Under ordinary conditions the rate of energy metabolism in cells is governed by ADP-feedback system, since other reactants (inorganic phosphate, substrate, oxygen, enzymes and co-factors) are present relative excess. 2. When supply oxygen severely limited, it may assume characteristics a rate-limiter, pattern as well be altered. 3. The quantitative estimation severity hypoxia more difficult problem than generally realized. The available approaches include: direct measurement tissue (perhaps intracellular) tension with micro-electrodes, oxidation-reduction status terms ratios oxidized reduced forms electron carrier components (e. g. NAD : NADH2), concentrations high compounds tissues, “excess lactate” concentration tissues. results these various methods not always agreement, cause this lack agreement an important to solved. 4. Other unsolved problems field relation between intracellular partition ATP-formation aerobic anaerobic pathways, possible conservation limited supplies ATP its selective utilization for those functions essential cell survival. 5. Adaptation chronic involve systemic adjustments which increase delivery cells, cellular enable survive decrease their supply. occurrence established, but controversial. 6. It concluded that becomes metabolic regulator only when falls very low levels indeed. 7. The responses condition severe deficiency (a) adaptive enzyme changes permit efficient (b) increased contribution metabolism, (c) most survival cells.