Muscarinic Signaling Pathways Affecting Cardiac Channels

影响心脏通道的毒蕈碱信号通路

• 批准号: 6368360
• 负责人: ROBERT D HARVEY
• 金额: $ 31.78万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-08-06 至 2005-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6368360
• 关键词: G protein; adenylate cyclase; age difference; beta adrenergic receptor; biological signal transduction; cardiac myocytes; cell type; cyclic AMP; fluorescence resonance energy transfer; guinea pigs; heart contraction; heart function; heart innervation; heart rate; immunocytochemistry; isozymes; laboratory mouse; muscarinic receptor; nitric oxide; receptor coupling; receptor expression; tissue /cell culture; voltage /patch clamp

DESCRIPTION (provided by applicant):Parasympathetic stimulation exerts significant influence on heart rate and contractility through the release of the neurotransmitter acetylcholine, which then activates muscarinic receptors found on all cardiac myocytes. These effects are mediated in whole or in part by direct and indirect signaling mechanisms affecting cardiac ion channel activity. The indirect effects involve modulation of cAMP-dependent beta-adrenergic responses. In fact, muscarinic receptor activation inhibits as well as facilitates beta-adrenergic responses, suggesting that the net result is a balance between these inhibitory and stimulatory effects. Recent evidence suggests that in atrial preparations, both the inhibitory and stimulatory effects are mediated solely by the production of nitric oxide (NO). However, this signaling mechanism may not be as important in mediating muscarinic responses in adult ventricular myocytes. Our working hypothesis is that there is developmental regulation of the signaling pathway coupling muscarinic receptors to modulation of beta-adrenergic responses, which may lead to cell type specific signaling mechanisms in the adult heart. If this is the case, then what is responsible for muscarinic responses in adult ventricular myocytes? There is uncontested evidence that the inhibitory effects can be explained by direct G-dependent inhibition of adenylyl cyclase types V and/or VI (AC5 and AC6). However, we propose the novel idea that the stimulatory effects are due to direct G-dependent stimulation of AC4 and/or AC7. Therefore the specific aims of this proposal are to test the following four hypotheses: 1) NO does not contribute to either muscannic inhibitory or muscarinic stimulatory responses in adult ventricular myocytes; 2) muscarinic stimulatory responses in adult ventricular myocytes are due to direct G protein dependent activation of specific AC isoforms; 3) NO does contribute to muscarinic inhibitory and muscannic stimulatory signaling mechanisms in atrial myocytes; and 4) NO is also involved in muscarinic signaling mechanisms in neonatal ventricular myocytes. We will use control and genetically altered animal models to identify the signaling pathways involved in mediating muscarinic responses by recording CAMP regulated cardiac ion channel activity in conjunction with direct fluorescence measurements of cAMP activity in isolated cardiac myocytes.

描述（申请人提供）：副交感神经刺激施加 通过发布对心率和收缩性的重大影响 神经递质乙酰胆碱，然后激活毒蕈碱受体 在所有心肌细胞上发现。这些效果是全部或部分介导的 通过影响心脏离子通道的直接和间接信号传导机制 活动。间接效应涉及camp依赖性的调制 β-肾上腺素能反应。实际上，毒蕈碱受体激活抑制 并促进β-肾上腺素能反应，表明净结果 是这些抑制作用和刺激作用之间的平衡。最近的证据 表明在心房制剂中，抑制性和刺激性 效果仅由一氧化氮的产生（NO）介导。然而， 这种信号传导机制对于介导毒蕈碱可能不那么重要 成人心室肌细胞的反应。我们的工作假设是 是信号通路耦合毒蕈碱的发育调节 受体调节β-肾上腺素反应，这可能导致细胞 在成人心脏中输入特定的信号传导机制。如果是这样， 那么是什么原因导致成人心室的毒蕈碱反应 心肌细胞？有没有争议的证据表明抑制作用可以是 通过直接g依赖性抑制腺苷酸环化酶类型和/或 VI（AC5和AC6）。但是，我们提出了刺激性的新颖想法 效果是由于AC4和/或AC7的直接G依赖性刺激。所以 该提案的具体目的是检验以下四个假设： 1）否不会造成肌肉抑制或毒蕈碱 成人心室心肌细胞的刺激反应； 2）毒蕈碱刺激性 成年心室肌细胞的反应是由于直接G蛋白依赖于G蛋白 特定AC同工型的激活； 3）不为毒蕈碱做出贡献 心肌细胞中的抑制性和肌肉刺激信号传导机制； 4）NO也参与新生儿的毒蕈碱信号传导机制 心肌细胞。我们将使用控制和遗传改变的动物模型 确定介导毒蕈碱反应涉及的信号通路 通过记录营地调节的心脏离子通道活动与 孤立心肌细胞中cAMP活性的直接荧光测量。