REGULATION OF CALCIUM-ACTIVATED CHLORIDE CHANNELS

钙激活的氯(CAC)通道在许多 生理过程，包括呼吸道上皮的分泌， 心脏动作电位复极，血管张力调节， 和神经元兴奋性。这些通道在几个人类身上都很重要 疾病，包括囊性纤维化和心律失常。我们的理解 然而，CAC通道的生物物理学仍处于初级阶段，而且 钙激活钙通道的机制是个谜。这项建议旨在 非洲爪哇CAC通道调控和门控机制的研究 单通道水平的卵母细胞和兔心肌细胞贴片 细胞贴附和切除贴片配置中的钳制技术。这些 研究将为这一过程的控制和功能提供重要的见解 一类重要的离子通道，并可能对 了解钙是如何调节其他类型的离子通道的。目标1 解决CAC通道和电流的明显多样性是否源于 通道类型的分子多样性或CAC通道的复杂性 监管。非洲爪哇卵母细胞是研究这一问题的理想系统。 因为它们表达了三种不同类型的CAC电流。我们拿出证据 CAC通道表现出强烈的电压依赖性钙敏感性，而WE 提出至少部分CAC电流的差异可以用以下方式解释 这种电压依赖性导致通道函数中的复杂性 钙的调节作用。目标2.阐述这一复杂的监管是如何产生的，通过 探讨钙离子结合、钙调素结合、钙调素对钙离子通道的调节机制。 以及通过磷酸化。目标2随后将这些研究扩展到心肌细胞。 CAC通道在心脏动作复极中起正常作用 也可能在引发心律失常中起到病理作用。 在钙超载期间。此目标的目标是描述CAC渠道的特征 心肌细胞了解是否相同的CAC通道负责 用于动作电位复极和触发的后除极 心律失常和探索通道调节的特点，允许 CAC通道变得致心律失常。

Ca-activated Cl (CaC) channels play fundamental roles in many physiological processes, including secretion in airway epithelium, repolarization of the cardiac action potential, regulation of vascular tone, and neuronal excitability. These channels are important in several human diseases, including cystic fibrosis and cardiac arrhythmias. Our understanding of the biophysics of CaC channels, however, remains rudimentary, and the mechanisms of CaC channel activation by Ca are enigmatic. This proposal aims to elucidate the mechanism of regulation and gating of CaC channels in Xenopus oocytes and rabbit cardiac myocytes at the single channel level using the patch clamp technique in the cell-attached and excised-patch configurations. These studies will provide important insights into the control and function of this important class of ion channels and will likely have an impact on the understanding of how other types of ion channels are regulated by Ca. Aim 1 addresses whether the apparent diversity in CaC channels and currents is due to molecular diversity in channel types or to complexity of CaC channel regulation. Xenopus oocytes are an ideal system for studying this question because they express three different types of CaC currents. We present evidence that CaC channels exhibit strong voltage-dependent Ca sensitivity and we suggest that at least some of the diversity in CaC currents can be explained by the complexities in channel function that result from this voltage-dependence of Ca regulation. Aim 2. Addresses how this complex regulation comes about, by examining the mechanisms of channel regulation by Ca binding, by CaM binding, and by phosphorylation. Aim 2 then extends these studies to cardiac myocytes. CaC channels play a normal role in repolarization of the cardiac action potential and can also play a pathological role in initiating arrhythmias during Ca overload. The goal of this aim is to characterize CaC channels in cardiac myocytes to understand whether the same CaC channels are responsible for action potential repolarization and the after depolarizations that trigger arrhythmias and to explore the features of channel regulation that permit the CaC channel to become arrhythmogenic.