IONIC BASIS OF EXCITABILITY IN INTRINSIC CARDIAC NEURONS

副交感神经元兴奋性的离子机制 神经节的哺乳动物心脏和行动的神经递质对他们的 功能将被研究。 神经递质影响神经元的功能， 各种离子通道和细胞内蛋白质在兴奋细胞， 改变静止和活动的电特性，因此， 细胞的生理反应。 电压依赖性和受体- 在分离的神经节细胞中，将研究操作离子通道 由从心房解剖的心内神经节的外植体制备 新生大鼠心肌，并在组织培养中生长。 主 目的是研究神经递质对神经元的作用机制， 心脏神经元中的受体操纵和电压门控离子通道， 随后细胞质游离钙浓度（[Ca 2 +]i）的变化， 膜兴奋性 实验将侧重于分子机制 肾上腺素能和肽能调节神经元电压依赖性 离子通道的渗透性，并激活的离子通道的渗透性 神经递质，乙酰胆碱和三磷酸腺苷（ATP）。 受体操纵的阳离子通道，其功能是允许Ca 2+进入 在这些激动剂激活期间，将通过单通道检测 记录以确定离子选择性、门控动力学和 受体通道功能中的细胞内第二信使。 的 受体激活对离子通道活性和[Ca ~（2+）]i影响 在加载有荧光Ca 2+的电压钳位神经元中进行评价 指示剂染料Indo-1，以同时监测[Ca 2 +]i荧光， 膜电流 具体而言，受体的相对贡献- 介导的Ca 2+进入和Ca 2+从细胞内储存释放 生化第二信使将在实验中评估， 第二信使的各种候选者（例如，Ca 2+，环状 核苷酸、花生四烯酸代谢物、肌醇磷酸、鸟嘌呤 核苷酸）通过直接应用于细胞质来操纵， 膜片钳方法。 这项研究的目的是阐明 心脏神经元中离子通道功能的基础机制以及 神经递质在哺乳动物神经元兴奋性调节中的作用 心脏副交感神经节

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.