IONIC BASIS OF EXCITABILITY IN INTRINSIC CARDIAC NEURONS

副交感神经元兴奋性的离子机制 哺乳动物心脏的神经节和神经递质对它们的作用 功能将被研究。神经递质影响细胞的功能 可兴奋细胞内离子通道和细胞内蛋白的变化 改变静息和活动的电属性，因此， 细胞的生理反应。电压依赖和受体- 将在分离的神经节细胞中研究操作的离子通道 取自心房的心内神经节外植体 新生大鼠心肌组织培养。初级阶段 目的：研究神经递质在脑出血中的作用机制。 受体操作和电压门控离子通道在心脏神经元和 细胞内游离钙浓度([Ca~(2+)]i)的动态变化 膜兴奋性。实验将集中在分子机制上。 肾上腺素能和肽能对神经元电压依赖性的调节作用 通道和离子通道的通透性 神经递质、乙酰胆碱和三磷酸腺苷(ATP)。 受体操作的阳离子通道，其功能是允许钙离子内流 在这些激动剂的激活过程中，将通过单通道进行检查 记录以确定离子选择性、门控动力学和作用 受体-通道功能中的细胞内第二信使。这个 受体激活对离子通道活性和[Ca~(2+)]i的影响 在钙离子荧光负荷下的电压钳制神经元中的评价 指示剂染料Indo-1，可同时监测[Ca~(2+)]i荧光和 膜电流。具体来说，受体的相对贡献- 介导细胞内钙离子的内流和释放 生化第二信使将在下列实验中进行评估 第二信使的各种候选者(例如，钙离子，环状 核苷酸、花生四烯酸代谢物、肌醇磷酸盐、鸟嘌呤 核苷酸)是通过直接施加到细胞质上来操纵的 膜片钳方法。这项研究的目的是阐明 心脏神经元离子通道功能的基础机制和 神经递质在哺乳动物神经元兴奋性调节中的作用 副交感神经节。

The ionic mechanisms underlying excitability in neurons of parasympathetic ganglia of the mammalian heart and the action of neurotransmitters on their function will be studied. Neurotransmitters influence the function of a variety of ion channels and intracellular proteins in excitable cells to alter resting and active electrical properties and, hence, the physiological responses of the cell. Voltage-dependent and receptor- operated ion channels will be studied in dissociated ganglion cells prepared from explants of intracardiac ganglia dissected from the atrial myocardium of newborn rats and grown in tissue culture. The primary objective is to study the mechanisms of action of neurotransmitters on receptor-operated and voltage-gated ion channels in cardiac neurons and subsequent changes in cytoplasmic free calcium concentration ([Ca2+]i) on membrane excitability. Experiments will focus on the molecular mechanisms of adrenergic and peptidergic modulation of neuronal voltage-dependent channels and on the permeability of the ion channels activated by the neurotransmitters, acetylcholine and adenosine triphosphate (ATP). Receptor-operated cation channels which function to permit Ca2+ entry during activation by these agonists will be examined by single channel recording to determine the ionic selectivity, gating kinetics and role of intracellular second messengers in receptor-channel function. The influence of receptor activation on ion channel activity and [Ca2+]i will be evaluated in voltage clamped neurons loaded with the fluorescent Ca2+ indicator dye, Indo-1, to simultaneously monitor [Ca2+]i fluorescence and membrane currents. Specifically, the relative contributions of receptor- mediated Ca2+ entry and Ca2+ release from intracellular stores by biochemical second messengers will be assessed in experiments in which various candidates for the second messenger (e.g., Ca2+, cyclic nucleotides, arachidonate metabolites, inositol phosphates, guanine nucleotides) are manipulated by direct application to the cytoplasm with the patch clamp method. The goal of the research is to elucidate mechanisms that underlie ion channel function in cardiac neurons and the role of neurotransmitters in regulating neuronal excitability in mammalian parasympathetic cardiac ganglia.