Zahradníková A, Zahradník I
Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Vlárska 5, 833 34, Bratislava, Slovak Republic.
Biochim Biophys Acta. 1999 May 12;1418(2):268-84. doi: 10.1016/s0005-2736(99)00036-x.
The planar lipid bilayer and vesicle release experiments are two alternative approaches used to study the function of the ryanodine receptor (RyR) channel at the subcellular level. In this work, we combine models of gating (Zahradníková and Zahradník, Biophys. J. 71 (1996) 2996-3012) and permeation (Tinker et al., J. Gen. Physiol. 100 (1992) 495-517) of the cardiac RyR channel to simulate calcium release experiments on sarcoplasmic reticulum vesicles. The resulting model and real experimental data agreed well within the experimental scatter, confirming indistinguishable properties of the RyRC in the vesicle preparation and in the planar lipid bilayer. The previously observed differences in calcium dependencies of the release and the gating processes can be explained by binding of calcium within the RyRC conducting pore. A novel method of analysis of calcium dependence of calcium release was developed and tested. Three gating models of the RyRC, showing, respectively, an increase, no change, and a decrease in calcium sensitivity over time, were compared. The described method of analysis enabled determination of temporal changes in calcium sensitivity, giving potential for detection of the adaptation/inactivation phenomena of the RyRC in both vesicle and in situ release experiments.
平面脂质双层和囊泡释放实验是用于在亚细胞水平研究兰尼碱受体（RyR）通道功能的两种替代方法。在这项工作中，我们结合了心脏RyR通道的门控模型（Zahradníková和Zahradník，《生物物理杂志》71 (1996) 2996 - 3012）和通透模型（Tinker等人，《普通生理学杂志》100 (1992) 495 - 517），以模拟肌浆网囊泡上的钙释放实验。所得模型与实际实验数据在实验误差范围内吻合良好，证实了在囊泡制剂和平面脂质双层中RyRC的特性难以区分。先前观察到的释放和门控过程钙依赖性差异可通过钙在RyRC传导孔内的结合来解释。我们开发并测试了一种分析钙释放钙依赖性的新方法。比较了RyRC的三种门控模型，它们分别显示钙敏感性随时间增加、不变和降低。所描述的分析方法能够确定钙敏感性的时间变化，为在囊泡和原位释放实验中检测RyRC的适应/失活现象提供了可能。
