Simpson D P, Hager S R
Am J Physiol. 1984 Sep;247(3 Pt 2):F440-6. doi: 10.1152/ajprenal.1984.247.3.F440.
The influence of the bicarbonate-carbon dioxide buffer system on the pH gradient (delta pH) across the inner membrane of mitochondria from rabbit renal cortex was studied with and without phosphate in the medium. delta pH with bicarbonate buffer or phosphate in the medium was greater at low than at high medium pH so that the difference (delta delta pH) between delta pH at pH 7.1 and at 7.6 was positive. Varying the concentration of phosphate from 0 to 10 mM had little effect on delta delta pH produced by bicarbonate buffer. Inhibition of the phosphate-hydroxyl carrier with N-ethylmaleimide abolished delta delta pH when phosphate was present in non-bicarbonate-containing media. With bicarbonate buffer present, N-ethylmaleimide increased delta delta pH. Similar effects were observed in mitochondria from liver and heart as well as from kidney. The effects of the bicarbonate buffer system on delta pH may result either from an inner membrane permeable to carbon dioxide but not to bicarbonate ion or from an active carrier for bicarbonate ion in the inner membrane. In intact kidney cells, the influence of the bicarbonate buffer system on delta pH may provide a mechanism for regulating substrate metabolism in response to acid-base changes. It may also serve in many organs to reduce fluctuations in matrix pH when alterations in cytoplasmic pH occur.
研究了碳酸氢盐 - 二氧化碳缓冲系统对兔肾皮质线粒体内膜跨膜pH梯度（ΔpH）的影响，实验分培养基中有无磷酸盐两种情况。培养基中含有碳酸氢盐缓冲液或磷酸盐时，低培养基pH下的ΔpH高于高培养基pH下的ΔpH，因此pH 7.1和7.6时的ΔpH之差（ΔΔpH）为正值。将磷酸盐浓度从0变化到10 mM，对碳酸氢盐缓冲液产生的ΔΔpH影响不大。在不含碳酸氢盐的培养基中存在磷酸盐时，用N - 乙基马来酰亚胺抑制磷酸盐 - 羟基载体可消除ΔΔpH。存在碳酸氢盐缓冲液时，N - 乙基马来酰亚胺会增加ΔΔpH。在肝、心以及肾的线粒体中均观察到类似效应。碳酸氢盐缓冲系统对ΔpH的影响可能源于内膜对二氧化碳可通透但对碳酸氢根离子不通透，或者源于内膜中存在碳酸氢根离子的活性载体。在完整的肾细胞中，碳酸氢盐缓冲系统对ΔpH的影响可能为响应酸碱变化调节底物代谢提供一种机制。当细胞质pH发生改变时，它也可能在许多器官中起到减少基质pH波动的作用。
