Dahlem Yuliya A, Wolf Gerald, Siemen Detlef, Horn Thomas F W
Institute of Medical Neurobiology, Otto-von-Guericke University Magdeburg, Leipzigerstr. 44, D-39120 Magdeburg, Germany.
Cell Calcium. 2006 May;39(5):387-400. doi: 10.1016/j.ceca.2006.01.001. Epub 2006 Mar 2.
The permeability transition pore (PTP) and the ATP-dependent potassium (mtK-ATP) channel of mitochondria are known to play key roles in mitochondrially mediated apoptosis. We investigated how modulation of the permeability transition pore (PTP) and the ATP-dependent potassium (mtK-ATP) channel, either as single elements or in combination, affects the proapoptotic intracellular calcium (Ca(2+)) transients and the mitochondrial membrane potential (psi(m)). For this purpose a model was established exploring the Ca(2+) transients in N2A cells using continuous application of ATP that causes a biphasic Ca(2+) response. This response was sensitive to endoplasmatic reticulum (ER) Ca(2+) depletion and a smooth ER Ca(2+)-ATPase (SERCA) antagonist. PTP inhibition by cyclosporine A (CsA) or its non-immunosuppressive derivative NIM811 caused an amplification of the secondary Ca(2+) peak and induced a hyperpolarization of psi(m). Both the putative mtK-ATP channel inhibitor 5-hydroxydecanoate (5-HD) and the opener diazoxide ameliorated the ATP-induced secondary Ca(2+) peak. The effect of diazoxide was accompanied by a depolarization of psi(m) whereas 5-HD had no effect on psi(m). When diazoxide and CsA or NIM811 were applied together the secondary Ca(2+) rise did not return to baseline and a not significant hyperpolarization of psi(m) was observed. So, simultaneous inhibition of PTP and activation of the mtK-ATP channel prevents the increased slope of the secondary Ca(2+) peak induced by CsA (or NIM811) and also the depolarization after diazoxide application. Hence, we propose that modulation of one of these channels leads to functional changes of the other channel by means of DeltaCa(2+) and Deltapsi(m).
线粒体通透性转换孔（PTP）和线粒体ATP依赖性钾通道（mtK-ATP）在介导线粒体凋亡中发挥关键作用。我们研究了单独或联合调节通透性转换孔（PTP）和ATP依赖性钾通道（mtK-ATP）如何影响促凋亡细胞内钙（Ca(2+)）瞬变和线粒体膜电位（psi(m)）。为此，建立了一个模型，通过持续应用ATP来探索N2A细胞中的Ca(2+)瞬变，ATP会引起双相Ca(2+)反应。该反应对内质网（ER）钙耗竭和平滑内质网钙ATP酶（SERCA）拮抗剂敏感。环孢素A（CsA）或其非免疫抑制衍生物NIM811对PTP的抑制导致继发性Ca(2+)峰值放大，并诱导psi(m)超极化。推测的mtK-ATP通道抑制剂5-羟基癸酸（5-HD）和开放剂二氮嗪均改善了ATP诱导的继发性Ca(2+)峰值。二氮嗪的作用伴随着psi(m)的去极化，而5-HD对psi(m)无影响。当二氮嗪与CsA或NIM811一起应用时，继发性Ca(2+)升高未恢复到基线水平，且观察到psi(m)有不显著的超极化。因此，同时抑制PTP和激活mtK-ATP通道可防止CsA（或NIM811）诱导的继发性Ca(2+)峰值斜率增加以及二氮嗪应用后的去极化。因此，我们提出调节这些通道之一会通过DeltaCa(2+)和Deltapsi(m)导致另一个通道的功能变化。
