Lundgren T, Linde A
Department of Oral Biochemistry, Faculty of Odontology, Göteborg University, P.O. Box 451, S-405 30 Göteborg, Sweden.
Biochim Biophys Acta. 1998 Sep 2;1373(2):341-6. doi: 10.1016/s0005-2736(98)00124-2.
In addition to the Ca2+ portion freely dissociated in the cytosol, another Ca2+ pool is associated with plasma membranes and intracellular organelle membranes. This Ca2+ portion is of importance for regulation of, among other things, the cell cycle, actin-mediated processes, and cell morphology. In the literature, dihydropyridines have been reported to influence this membrane-associated pool of Ca2+ under certain conditions. The aim of this investigation was to study possible modulations of plasma membrane-associated Ca2+ upon treatment with nifedipine in vitro in a Ca2+-transporting cell, the dentin-forming odontoblast. The membrane-associated portion of Ca2+ in dissected dentinogenically active rat incisor odontoblasts was monitored by fluorescence spectrophotometry using chlortetracycline as a probe. In addition, images of chlortetracycline-Ca2+ binding were obtained by fluorescence microscopy. It was found that membrane-associated Ca2+ decreased by the dihydropyridine nifedipine, whereas this Ca2+ pool was unaffected by the cellular polarization state, which was in contrast to cytosolic free Ca2+ as measured by fura-2. The results show that the odontoblast plasma membrane-associated Ca2+-pool can be modulated by nifedipine, thus being dependent on the conformational state of the L-type Ca2+ channels.
除了在细胞质中自由解离的钙离子部分外，另一个钙离子池与质膜和细胞内细胞器膜相关。这部分钙离子对于调节细胞周期、肌动蛋白介导的过程以及细胞形态等诸多方面都很重要。在文献中，据报道二氢吡啶在某些条件下会影响这个与膜相关的钙离子池。本研究的目的是在体外研究用硝苯地平处理钙离子转运细胞——形成牙本质的成牙本质细胞后，质膜相关钙离子可能发生的调节情况。使用金霉素作为探针，通过荧光分光光度法监测解剖的具有牙本质形成活性的大鼠切牙成牙本质细胞中与膜相关的钙离子部分。此外，通过荧光显微镜获得金霉素 - 钙离子结合的图像。结果发现，二氢吡啶硝苯地平会使与膜相关的钙离子减少，而这个钙离子池不受细胞极化状态的影响，这与用fura - 2测量的细胞质游离钙离子情况相反。结果表明，成牙本质细胞质膜相关的钙离子池可被硝苯地平调节，因此依赖于L型钙离子通道的构象状态。
