CALMODULIN-DEPENDENT PROTEIN KINASE II IN HEART CALCIUM CHANNEL REGULATION

心肌细胞膜Ca ~（2+）通道的Ca ~（2+）电流 是细胞内钙稳态的重要决定因素，因此是重要的 决定了多种细胞功能。 而Ca ~（2+）和膜 钙离子通道的电压依赖性正调控已经被 最近报道，很少有人知道的机制。 我们的研究 提供了令人信服的证据表明，在成年大鼠的心室细胞中， 钙/钙调蛋白依赖性激酶II介导L型钙电流 促进作用，即，电流强度的增加和/或减缓 在重复去极化过程中，通过单一的强 去极化预脉冲或去极化保持电位。 所有 这些对电流的影响被包含在 钙/钙调蛋白激酶II的特异性肽抑制剂， 用移液管填充溶液或通过用Ba 2+替换Ca 2+， 浴液 Ca ~（2+）/钙调蛋白激酶II参与Ca ~（2+） 本地化分布进一步支持了电流调节 细胞肌膜附近激酶的特异性抗体， 通过数字共焦荧光成像。 而且 抗体的免疫荧光显著增强， 高[K+]o去极化，并通过去除Ca 2 +o或 W7是一种钙调蛋白抑制剂。 因此，Ca 2 +/钙调蛋白激酶II 依赖性蛋白磷酸化是一种重要的机制， 可变因素，如Ca 2+，重复刺激和强 去极化可正向调节心肌细胞内钙电流， 膜电位在调节 激酶活性。 这些发现提供了新的见解， 了解心肌细胞中的Ca 2+通道调节， 其他细胞类型也是如此。

Ca2+ current flowing via sarcolemmal Ca2+ channels of heart cells is an important determinant of cell Ca2+ homeostasis and thus an important determinant of a variety of cell functions. While Ca2+- and membrane voltage-dependent positive regulation of Ca2+ channels have been recently reported, little is known of the mechanism. Our studies provide compelling evidence that in adult rat cardiac ventricular cells Ca2+/calmodulin dependent kinase II mediates L-type Ca2+ current facilitation, i.e., an augmentation in current magnitude and or slowing of its inactivation during repetitive depolarizations, by single strong depolarizing prepulse or by depolarizing holding potentials. All of these effects on the current were completely abolished by a inclusion of specific peptide inhibitor of Ca2+/calmodulin kinase II within the pipette filling solution or by the replacement of Ca2+ with Ba2+ in bath solution. The involvement of Ca2+/calmodulin kinase II on Ca2+ current regulation is further supported by the localized distribution of a specific antibody to the kinase near cell sarcolemma as revealed by digital confocal fluorescent imaging. Furthermore, the immunofluorescence of the antibody was significantly enhanced by depolarization with high [K+]o and attenuated by removal of Ca2+o or by W7, a calmodulin inhibitor. Thus, Ca2+/calmodulin kinase II dependent protein phosphorylation is an important mechanism by which variable factors, such as Ca2+, repetitive stimulation and strong depolarization can positively regulate Ca2+ current in heart cells, and that membrane potential plays an essential role in the modulation of the kinase activity. These findings provide new insights toward understanding Ca2+ channel regulation in cardiac cells as possibly in other cell types as well.