Metabolic and energy correlates of intracellular pH in progressive fatigue of squid (L. brevis) mantle muscle.
Metabolic and energy correlates of intracellular pH in progressive fatigue of squid (L. brevis) mantle muscle.
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鱿鱼（L. brevis）外套膜肌肉进行性疲劳时细胞内 pH 值的代谢和能量相关性。
DOI：
10.1152/ajpregu.1996.271.5.r1403
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Lee,PG
中科院分区：
文献类型：
--
作者：
Portner,HO;Finke,E;Lee,PG
为了分析外套膜肌肉细胞内代谢、酸碱和能量状态的相关变化，我们在提高游泳速度的情况下对鱿鱼(Loliguncula Brevis)进行了锻炼。超过临界游泳速度1.5地幔长度/S后，细胞内发生酸中毒，这是由于细胞最初的碱基丢失，呼吸性酸化的开始，以及主要是章鱼的形成。酸中毒与磷酸-L-精氨酸水平下降有关，因此，以牺牲磷酸原为代价，支持了三磷酸腺苷的缓冲。一氢磷酸，糖原磷酸化酶的实际底物积累，使糖原降解，尽管进行性酸中毒。除了章鱼碱、琥珀酸和甘油磷酸蓄积外，酸中毒的开始是临界速度的特征，并预示着向非稳态时间限制情况的转变。相应地，高于临界速度的游泳导致细胞能级(体内ATP水解的吉布斯自由能变化)下降。在-45kJ/mol左右达到最小值。模型计算表明，游离镁离子水平的变化对ATP自由能的影响很小，但最低水平与维持镁(2+)络合腺苷的功能浓度有关。模型计算还显示，磷原物质的分解使L.brevis能够达到大约三倍于临界速度的游泳速度。两种近海鱿鱼(Lolio pealei和Illex illebrosus)与河口鱿鱼L.brevis的比较表明，后者采用了一种策略来推迟高能磷酸盐的开发，并在高于其他物种疲劳特征的最低水平(-42kJ/mol)时保护能量水平。更经济地利用厌氧资源和及早降低性能可能使短小乳杆菌能够容忍浅水河口水域甚至低氧环境中更极端的环境条件，并防止能量储备的致命消耗。
Squid (Lolliguncula brevis) were exercised at increasing swimming speeds to allow us to analyze the correlated changes in intracellular metabolic, acid-base, and energy status of the mantle musculature. Beyond a critical swimming velocity of 1.5 mantle lengths/s, an intracellular acidosis developed that was caused by an initial base loss from the cells, the onset of respiratory acidification, and, predominantly, octopine formation. The acidosis was correlated with decreasing levels of phospho-L-arginine and, thus, supported ATP buffering at the expense of the phosphagen. Monohydrogenphosphate, the actual substrate of glycogen phosphorylase accumulated, enabling glycogen degradation, despite progressive acidosis. In addition to octopine, succinate, and glycerophosphate accumulation, the onset of acidosis characterizes the critical velocity and indicates the transition to a non-steady-state time-limited situation. Accordingly, swimming above the critical velocity caused cellular energy levels (in vivo Gibbs free energy change of ATP hydrolysis) to fall. A minimal value was reached at about -45 kJ/mol. Model calculations demonstrate that changes in free Mg2+ levels only minimally affect ATP free energy, but minimum levels are relevant in maintaining functional concentrations of Mg(2+)-complexed adenylates. Model calculations also reveal that phosphagen breakdown enabled L. brevis to reach swimming speeds about three times higher than the critical velocity. Comparison of two offshore squid species (Loligo pealei and Illex illecebrosus) with the estuarine squid L.brevis indicates that the latter uses a strategy to delay the exploitation of high-energy phosphates and protect energy levels at higher than the minimum levels (-42 kJ/mol) characterizing fatigue in the other species. A more economical use of anaerobic resources and an early reduction in performance may enable L. brevis to tolerate more extreme environmental conditions in shallow estuarine waters and even hypoxic environments and to prevent a fatal depletion of energy stores.