HEART MUSCLE IONIC CURRENTS--CHOLINERGIC MECHANISMS

心脏跳动的力量和速度是通过释放来调节的 乙酰胆碱（ACh）和去甲肾上腺素（NE）的自主神经 神经系统，然而，这一分子机制 规则理解得很少。 虽然它是某些NE行为 ACh的作用机制部分是通过cAMP系统， 是未知的。 了解这些机制是很重要的 了解心脏的正常功能， 了解心脏病。 例如，T.N.詹姆斯和 其他人则认为心脏神经病变与某些类型的 突然死亡 乙酰胆碱通过激活超极化的 背景钾电流，并降低 收缩通过降低细胞内钙。 缓慢发作 和对ACh短脉冲的长持续时间反应表明 具有一个或多个酶促反应的多步机制。 的 在这个提议中的实验将测试ACh的假设， 激活钾电流和抑制钙电流 通过GTP结合蛋白偶联到各种 效应蛋白 该假设将在 受体/GTP蛋白质碰撞耦合模型框架 互动 全细胞和单通道电流将 用膜片钳在蛙心房和静脉窦中测量 方法. 一般的方法是灌注细胞 用各种分子探针在细胞内检测。 的实例 这种探针是GTP和GTP类似物、百日咳博德特氏菌，和 各种蛋白激酶的抑制剂和激活剂。 这项工作的结果将有助于了解 调节心脏的分子机制， 了解其他地方的胆碱能机制， 身体

The force and rate of the heart beat are regulated through release of acetylcholine (ACh) and norepinephrine (NE) by the autonomic nervous system, however, the molecular mechanisms of this regulation are poorly understood. While it is certain NE acts partly through the cAMP system the mechanisms of ACh action are unknown. An understanding of these mechanisms is important for understanding the normal functioning heart and for understanding cardiac disease. For example, T.N. James and others have implicated cardiac neuropathies with certain kinds of sudden death. ACh decreases heart rate by activating a hyperpolarizing background potassium current and decreases the force of contraction by decreasing intracellular calcium. The slow onset and long duration in response to a brief pulse of ACh suggest a multistep mechanism with one or more enzymatic reactions. The experiments in this proposal will test the hypothesis that ACh activation of potassium current and inhibition of calcium current in the heart occurs via coupling of GTP binding proteins to various effector proteins. The hypothesis will be tested within the framework of a collision-coupling model for receptor/GTP protein interaction. Whole cell and single channel currents will be measured in the frog atrium and sinus venosus by patch clamp methods. The general approach will be to perfuse cells intracellularly with a variety of molecular probes. Examples of such probes are GTP and GTP analogs, Bordetella pertussis, and inhibitors and activators of various protein kinases. The results from this work will contribute to the understanding of the molecular mechanisms which regulate the heart and facilitate an understanding of cholinergic mechanisms elsewhere in the body.