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目的:研究大鼠心室肌细胞在兴奋收缩耦联过程中诱发的钙释放(钙闪烁)的基本特征。方法:采用高敏感性线性扫描激光共聚焦显微镜、细胞内钙荧光染色和膜片箝技术研究自发的和由除极诱发的钙闪烁。结果:1)沿着细胞纵轴方向的激光共聚焦线性扫描显示自发的钙闪烁和由除极至-35mV诱发的钙闪烁均可在间隔约1.8μm(即肌小节的长度)的地方出现,由高斯曲线分布来测量它们纵轴分布(最大振幅一半的宽度,FWHM)的均值为2.6μm. 2)而采用横向的激光共聚焦线性扫描则常常发现自发和诱发的钙闪烁可从近乎对称的成对释放点产生。测量横向的自发和诱发的钙闪烁的FWHM呈双峰型分布,可以很好地由高斯双曲线拟合,其中自发的钙闪烁的均值为1.8和2.9μm,诱发的钙闪烁为 1.9和3.1μm。在二个高斯曲线下的相对面积为1.73:1(自发钙闪烁)及1.85:1(诱发钙闪烁)。结论:由去极化电流诱发的钙闪烁不是“单一”事件,而像我们以前报道的自发钙闪烁一样,常常涉及沿着Z线的多个起源位点。因此,通过L-型钙通道内流触发的钙闪烁释放的钙,继之可诱发相邻的位点。相邻几个横向释放位点限制性的介入钙释放,仍然保留了兴奋收缩耦联“局部调控学说”的主要特征。
OBJECTIVE: To study the basic characteristics of calcium release (calcium scintigraphy) induced by rat excitory and contractile coupling of ventricular myocytes. METHODS: Spontaneous and depolarizing calcium scintigraphy was studied using a high-sensitivity linear confocal laser scanning microscopy, intracellular calcium fluorescence staining and patch-clamp techniques. Results: 1) Laser confocal linear scans along the longitudinal axis of the cells showed spontaneous calcium scintillation and calcium scintigraphy induced by depolarization to -35 mV both at a distance of about 1.8 [mu] m (ie, the length of the muscle segments) Their mean longitudinal distribution (FWHM) measured by Gaussian distribution was 2.6 μm.2) With transverse confocal laser scanning, it is often found that both spontaneous and induced calcium scintillation can be detected from a nearly symmetrical Pairs of release points generated. The FWHM for measuring spontaneous and induced calcium scintillation in the transverse direction was bimodal and fitted well to Gaussian hyperbola, with mean spontaneous calcium scintillations 1.8 and 2.9 μm and induced calcium scintillations 1.9 and 3.1 μm . The relative area under two Gaussian curves was 1.73: 1 (spontaneous calcium scintillation) and 1.85: 1 (induced calcium scintillation). Conclusions: Calcium scintigraphy induced by depolarizing currents is not a “single” event, but as we previously reported, spontaneous calcium scintillation often involves multiple sites of origin along the Z-line. Therefore, calcium released by calcium scintillation triggered by L-type calcium channel influx can then induce adjacent sites. Restrictive interventional calcium release from several adjacent horizontal release sites still retains the main features of the “local regulatory theory” of excitatory-contractile coupling.