Yonuschot G, Vaughn J M, Novotny J F
Department of Biochemistry, University of New England, Biddeford, ME 04005.
J Mol Cell Cardiol. 1992 Oct;24(10):1079-88. doi: 10.1016/0022-2828(92)93173-h.
The purpose of this study was to determine whether an early increase in [Ca2+]i preceding generalized lysis of cardiomyocytes occurred during photodynamic permeabilization. A method was developed which facilitated the simultaneous measurement, in real time, of permeabilization of the sarcolemma to Ca2+ and Mn2+ during photodynamic action. Quin-2 loaded cells were illuminated in the presence of erythrosin B and the change in the fluorescence emission of the calcium-quin-2 complex was used to measure the rate and extent of change in [Ca2+]i. The same system was used in the presence of extracellular Mn2+ to determine how quickly the cardiomyocytes became permeable to either Mn2+ or quin-2. Calcium ions were observed to enter the myocytes prior to permeabilization of the sarcolemma to either Mn2+ or quin-2, and thus before membrane lysis. Lysis of cardiomyocytes did not appear to be dependent upon increases in [Ca2+]i. Controls were performed to rule out fluorescent artifacts. Reperfusion injury and photodynamic therapy involve both the production of free radicals and an early increase in [Ca2+]i. This study demonstrates a direct correlation between the production of reactive oxygen species and prelytic increases in [Ca2+]i in neonatal cardiomyocytes and demonstrates that this phenomenon may be common to many cell types.
本研究的目的是确定在光动力通透过程中，心肌细胞普遍裂解之前细胞内钙离子浓度（[Ca2+]i）是否会提前升高。我们开发了一种方法，该方法有助于在光动力作用期间实时同步测量肌膜对钙离子和锰离子的通透性。在赤藓红B存在的情况下，对负载有喹啉-2的细胞进行光照，并利用钙-喹啉-2复合物荧光发射的变化来测量[Ca2+]i的变化速率和程度。在细胞外存在锰离子的情况下，使用相同的系统来确定心肌细胞对锰离子或喹啉-2的通透速度。观察到钙离子在肌膜对锰离子或喹啉-2通透之前，也就是在膜裂解之前就进入了心肌细胞。心肌细胞的裂解似乎并不依赖于[Ca2+]i的升高。进行了对照实验以排除荧光假象。再灌注损伤和光动力疗法都涉及自由基的产生以及[Ca2+]i的早期升高。本研究证明了新生心肌细胞中活性氧的产生与裂解前[Ca2+]i升高之间存在直接关联，并表明这种现象可能在许多细胞类型中普遍存在。
