Martin A D, Titheradge M A
Biochem J. 1984 Sep 1;222(2):379-87. doi: 10.1042/bj2220379.
Hepatic mitochondria isolated in 0.3 M-sucrose or 0.3 M-mannitol from rats treated for 3h with dexamethasone displayed stimulated rates of pyruvate carboxylation and decarboxylation and citrulline synthesis when compared with organelles from control animals. Mitochondria isolated in mannitol also displayed elevated rates of pyruvate carboxylation and decarboxylation when compared with those isolated in sucrose, and this stimulation was shown to be independent of the lengthy isolation procedure. Citrulline synthesis proceeded at similar rates in mitochondria isolated in either sugar. The concentration of exchangeable adenine nucleotides was identical in mitochondria isolated in sucrose or mannitol, suggesting that those prepared in the former sugar are not more permeable to metabolites than those prepared in the latter. The matrix volume of mitochondria isolated in mannitol was greater than that of mitochondria isolated in sucrose, and the effect of mannitol on pyruvate metabolism was mimicked by swelling the organelles in hypo-osmotic sucrose. Measurements of the extra-matrix volume by using [14C]sucrose or [14C]mannitol suggest that mannitol can permeate mitochondria to a greater extent than can sucrose. The possibility that mannitol elicits its effect by entering the mitochondrial matrix and so initiating swelling is discussed.
与对照动物的细胞器相比，用0.3M蔗糖或0.3M甘露醇从经地塞米松处理3小时的大鼠中分离出的肝线粒体，其丙酮酸羧化、脱羧和瓜氨酸合成速率均受到刺激。与在蔗糖中分离的线粒体相比，在甘露醇中分离的线粒体的丙酮酸羧化和脱羧速率也有所提高，并且这种刺激与冗长的分离过程无关。在两种糖中分离的线粒体中，瓜氨酸合成速率相似。在蔗糖或甘露醇中分离的线粒体中，可交换腺嘌呤核苷酸的浓度相同，这表明在前者中制备的线粒体对代谢物的通透性并不比在后者中制备的线粒体更高。在甘露醇中分离的线粒体的基质体积大于在蔗糖中分离的线粒体，并且通过在低渗蔗糖中使细胞器膨胀可模拟甘露醇对丙酮酸代谢的影响。使用[14C]蔗糖或[14C]甘露醇测量线粒体外基质体积表明，甘露醇比蔗糖更能渗透线粒体。本文讨论了甘露醇通过进入线粒体基质并引发肿胀而发挥其作用的可能性。
