HEART MUSCLE IONIC CURRENTS--CHOLINERGIC MECHANISMS

心跳的力量和频率是通过释放来调节的 乙酰胆碱(ACh)和去甲肾上腺素(NE)的自主神经作用 神经系统，然而，这一分子机制 人们对监管知之甚少。虽然它是一定的NE行为 ACh的作用机制部分通过cAMP系统 都是未知的。了解这些机制是很重要的 为了了解正常运作的心脏和 了解心脏病。例如，T.N.James和 另一些人则认为心脏神经病变与某些类型的 猝死。 ACh通过激活超极化来降低心率 背景钾电流，并降低 通过减少细胞内钙而收缩。慢速起病 而对ACh短暂脉冲的长持续时间表明 具有一个或多个酶反应的多步骤机制。这个 这一方案中的实验将检验ACh的假设 钾电流的激活和钙电流的抑制 在心脏中通过GTP结合蛋白与各种 效应器蛋白。这一假设将在 受体/GTP蛋白碰撞偶联模型的框架 互动。整个电池和单通道电流将 膜片钳对蛙心房和静脉窦的测量 方法：研究方法。一般的方法将是给细胞灌流 细胞内使用各种分子探针。举例 这种探针是GTP和GTP类似物，百日咳杆菌，以及 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理解 调节心脏和促进心脏健康的分子机制 对心脏其他部位胆碱能机制的理解 尸体。

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.