Cellular levels of diadenosine tetraphosphate (Ap4A) were measured, by a specific high-pressure liquid chromatography method, in microplasmodia of Physarum polycephalum subjected to different degrees of hypoxia, hyperoxia, and treatment with H2O2. Ap4A levels increased three- to sevenfold under anaerobic conditions, and the microplasmodia remained viable after such treatment. Elevated levels of Ap4A returned to the basal level within 5 to 10 min upon reoxygenation of the microplasmodia. The increases in Ap4A levels were larger in stationary-phase or starved microplasmodia than in fed, log-phase microplasmodia. The maximal increase measured in log-phase microplasmodia was twofold. No significant changes in Ap4A levels occurred in microplasmodia subjected to mild hypoxia, hyperoxia, or treatment with 1 mM H2O2. These results indicate that in P. polycephalum, Ap4A may function in the metabolic response to anaerobic conditions rather than in the response to oxidative stress.
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机译：通过特定的高压液相色谱法，在经历了不同程度的缺氧，高氧和H2O2处理的多头Phys草的微胞浆菌中，通过特定的高压液相色谱法测量了细胞中四磷酸腺苷四磷酸（Ap4A）的水平。在厌氧条件下，Ap4A水平增加了三到七倍，经过这种处理后，微胞浆菌仍然可以存活。在微胞浆菌再充氧后的5至10分钟内，Ap4A的水平升高回到基础水平。在静止期或饥饿的微浆虫病中，Ap4A水平的升高大于在进食的对数期微浆虫病中。在对数期血浆中测得的最大增加是两倍。在轻度缺氧，高氧或用1 mM H2O2处理的微胞浆菌中，Ap4A水平没有明显变化。这些结果表明，在多头疟原虫中，Ap4A可能在对厌氧条件的代谢反应中起作用，而不是对氧化应激的反应中起作用。
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