Dissociation of acid-base effects on substrate accumulation and on delta pH in dog mitochondria.
Dissociation of acid-base effects on substrate accumulation and on delta pH in dog mitochondria.
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酸碱解离对狗线粒体底物积累和 Delta pH 的影响。
DOI：
10.1152/ajprenal.1988.254.6.f863
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
Simpson,DP
中科院分区：
文献类型：
--
作者：
Simpson,DP
在狗肾皮质线粒体中检查了 pH 梯度（δ pH）和底物积累之间的关系。线粒体在含有碳酸氢盐或非碳酸氢盐缓冲液的培养基中孵育。孵育 2 分钟后，线粒体 delta pH 达到平衡，但基质空间中柠檬酸盐的积累仍在增加。在鱼藤酮抑制的线粒体中使用非碳酸氢盐缓冲液时，基质中柠檬酸盐和 α-酮戊二酸盐的浓度在 pH 7.5 和 7.1 之间没有变化；随着培养基 pH 值下降，δ pH 值从 0.62 下降至 0.52。随着碳酸氢盐浓度的降低（从 40 至 10 mM）和恒定的 CO2 张力，柠檬酸盐、α-酮戊二酸盐、苹果酸盐、谷氨酸盐、谷氨酰胺和甲酸盐的浓度增加； 10 mM 碳酸氢盐积累量低于 25 mM 碳酸氢盐积累量； δ pH 值保持恒定。当呼吸发生变化时，柠檬酸盐、α-酮戊二酸盐、苹果酸盐和谷氨酸的浓度随着培养基 pH 值的下降和 CO2 张力的增加而增加；丙酮酸、谷氨酰胺和甲酸的积累不受影响。随着二氧化碳浓度从 3% 上升到 12%，δ pH 值从 0.48 下降到 0.39。在未受抑制的线粒体中，10 的标记柠檬酸盐比 40 mM 碳酸氢盐形成的 14CO2 更多；通过用 1,2,3-苯三羧酸盐抑制三羧酸盐载体，可以阻断这种差异以及柠檬酸盐在基质中的积累。这些结果将酸碱变化对线粒体底物积累的影响与 Delta pH 的变化分开。他们认为 pH 对多种线粒体底物载体具有直接的、依赖碳酸氢盐的影响。这种现象可能在肾皮质的代谢调节中发挥重要作用。
The relationship between the pH gradient (delta pH) and substrate accumulation was examined in mitochondria from dog renal cortex. Mitochondria were incubated in media containing bicarbonate or nonbicarbonate buffers. Mitochondrial delta pH was at equilibrium after 2 min incubation but citrate accumulation in the matrix space was still increasing. With nonbicarbonate buffer in rotenone-inhibited mitochondria, citrate and alpha-ketoglutarate concentrations in the matrix did not vary between pH 7.5 and 7.1; delta pH decreased from 0.62 to 0.52 as medium pH fell. With decreasing bicarbonate concentration (from 40 to 10 mM) and constant CO2 tension, concentrations of citrate, alpha-ketoglutarate, malate, glutamate, glutamine, and formate increased; pyruvate accumulation was lower at 10 than at 25 mM bicarbonate; delta pH remained constant. When respiratory changes were produced, concentrations of citrate, alpha-ketoglutarate, malate, and glutamate increased as medium pH fell and CO2 tension increased; accumulation of pyruvate, glutamine, and formate was unaffected. delta pH fell from 0.48 to 0.39 as CO2 tension rose from 3 to 12%. In uninhibited mitochondria, 14CO2 formation from labeled citrate was greater with 10 than with 40 mM bicarbonate; this difference as well as the accumulation of citrate in the matrix was blocked by inhibition of the tricarboxylate carrier with 1,2,3-benzenetricarboxylate. These results dissociate effects of acid-base change on mitochondrial substrate accumulation from changes in delta pH. They suggest a direct, bicarbonate-dependent influence of pH on multiple mitochondrial substrate carriers. This phenomenon may play an important role in metabolic regulation in renal cortex.