Lader A S, Kwiatkowski D J, Cantiello H F
Renal Unit, Massachusetts General Hospital East, Charlestown 02129, USA.
Am J Physiol. 1999 Dec;277(6):C1277-83. doi: 10.1152/ajpcell.1999.277.6.C1277.
The actin cytoskeleton is an important contributor to the modulation of the cell function. However, little is known about the regulatory role of this supermolecular structure in the membrane events that take place in the heart. In this report, the regulation of cardiac myocyte function by actin filament organization was investigated in neonatal mouse cardiac myocytes (NMCM) from both wild-type mice and mice genetically devoid of the actin filament severing protein gelsolin (Gsn-/-). Cardiac L-type calcium channel currents (I(Ca)) were assessed using the whole cell voltage-clamp technique. Addition of the actin filament stabilizer phalloidin to wild-type NMCM increased I(Ca) by 227% over control conditions. The basal I(Ca) of Gsn-/- NMCM was 300% higher than wild-type controls. This increase was completely reversed by intracellular perfusion of the Gsn-/- NMCM with exogenous gelsolin. Further, cytoskeletal disruption of either Gsn-/- or phalloidin-dialyzed wild-type NMCM with cytochalasin D (CD) decreased the enhanced I(Ca) by 84% and 87%, respectively. The data indicate that actin filament stabilization by either a lack of gelsolin or intracellular dialysis with phalloidin increase I(Ca), whereas actin filament disruption with CD or dialysis of Gsn-/- NMCM with gelsolin decrease I(Ca). We conclude that cardiac L-type calcium channel regulation is tightly controlled by actin filament organization. Actin filament rearrangement mediated by gelsolin may contribute to calcium channel inactivation.
肌动蛋白细胞骨架是细胞功能调节的重要贡献者。然而，对于这种超分子结构在心脏发生的膜事件中的调节作用知之甚少。在本报告中，研究了来自野生型小鼠和基因缺失肌动蛋白丝切断蛋白凝溶胶蛋白的小鼠（Gsn-/-）的新生小鼠心肌细胞（NMCM）中肌动蛋白丝组织对心肌细胞功能的调节。使用全细胞电压钳技术评估心脏L型钙通道电流（I(Ca)）。向野生型NMCM中添加肌动蛋白丝稳定剂鬼笔环肽，使I(Ca)比对照条件增加了227%。Gsn-/- NMCM的基础I(Ca)比野生型对照高300%。用外源性凝溶胶蛋白对Gsn-/- NMCM进行细胞内灌注可完全逆转这种增加。此外，用细胞松弛素D（CD）对Gsn-/-或经鬼笔环肽透析的野生型NMCM进行细胞骨架破坏，分别使增强的I(Ca)降低了84%和87%。数据表明，缺乏凝溶胶蛋白或用鬼笔环肽进行细胞内透析使肌动蛋白丝稳定会增加I(Ca)，而用CD破坏肌动蛋白丝或用凝溶胶蛋白对Gsn-/- NMCM进行透析会降低I(Ca)。我们得出结论，心脏L型钙通道的调节受到肌动蛋白丝组织的严格控制。由凝溶胶蛋白介导的肌动蛋白丝重排可能有助于钙通道失活。
