Bolshakov Alexey P, Mikhailova Maria M, Szabadkai György, Pinelis Vsevolod G, Brustovetsky Nickolay, Rizzuto Rosario, Khodorov Boris I
Institute of General Pathology and Pathophysiology RAMS, Baltiiskaya Street 8a, Moscow, Russia.
Cell Calcium. 2008 Jun;43(6):602-14. doi: 10.1016/j.ceca.2007.10.005. Epub 2007 Nov 26.
To clarify the role of the mitochondrial permeability transition pore (MPT) in the mechanism of the glutamate-induced delayed calcium deregulation (DCD) and mitochondrial depolarization (MD), we studied changes in cytosolic (pH(c)) and mitochondrial pH (pH(m)) induced by glutamate in cultured cortical neurons expressing pH-sensitive fluorescent proteins. We found that DCD and MD were associated with a prominent pH(m) decrease which presumably resulted from MPT opening. This pH(m) decrease occurred with some delay after the onset of DCD and MD. This argued against the hypothesis that MPT opening plays a dominant role in triggering of DCD. This conclusion was also supported by experiments in which Ca(2+) was replaced with antagonist of MPT opening Sr(2+). We found that in Sr(2+)-containing medium glutamate-induced delayed strontium deregulation (DSD), similar to DCD, which was accompanied by a profound MD. Analysis of the changes in pH(c) and pH(m) associated with DSD led us to conclude that MD in Sr(2+)-containing medium occurred without involvement of the pore. In contrast, in Ca(2+)-containing medium such "non-pore mechanism" was responsible only for MD initiation while in the final stages of MD development the MPT played a major role.
为了阐明线粒体通透性转换孔（MPT）在谷氨酸诱导的延迟性钙失调（DCD）和线粒体去极化（MD）机制中的作用，我们研究了在表达pH敏感荧光蛋白的培养皮层神经元中，谷氨酸诱导的胞质pH（pH(c)）和线粒体pH（pH(m)）的变化。我们发现DCD和MD与显著的pH(m)降低有关，这可能是由于MPT开放所致。这种pH(m)降低在DCD和MD开始后有一定延迟才出现。这与MPT开放在触发DCD中起主导作用的假设相悖。这一结论也得到了用MPT开放拮抗剂Sr(2+)替代Ca(2+)的实验的支持。我们发现，在含Sr(2+)的培养基中，谷氨酸诱导的延迟性锶失调（DSD），类似于DCD，伴有严重的MD。对与DSD相关的pH(c)和pH(m)变化的分析使我们得出结论，含Sr(2+)培养基中的MD发生时未涉及该孔。相反，在含钙(2+)的培养基中，这种“非孔机制”仅负责MD的起始，而在MD发展的最后阶段，MPT起主要作用。
