ROLE OF PROTEIN PHOSPHORYLATION IN CULTURED HEART CELLS

本研究的主要目的是研究心肌磷蛋白在心肌细胞中的作用。 心功能和兴奋性的调节。这些研究是 提出检验心脏磷蛋白调节的假说 介导钙、钾通透性变化的心功能 以及收缩的力量和速度，以及 磷蛋白是β-肾上腺素能受体相互作用的场所 和毒扁豆碱胆碱能传入心脏。拟议的研究将 用鸡胚胎心脏培养的单层心脏细胞， 提供了允许以短于 5秒，因此能够获得准确的时间进程 分析。这些研究的具体目标是确定是否： 1)心肌钙通道的一个亚单位在 对异丙肾上腺素的反应并介导钙内流增加 (以45Ca+内流率衡量)和收缩能力；2)密切相关 在磷酸化的出现的时间进程之间存在 钙通道亚单位和其他磷蛋白(蛋白C和 磷蛋白)和各自生理发育的进程 响应以及时间之间是否也存在密切的相关性 这些蛋白质的磷酸化的逆转过程和 逆转各自的生理反应；3)毒鼠碱激动剂 卡巴胆碱拮抗异丙肾上腺素刺激的生理反应 使钙通道亚单位、磷蛋白和蛋白C去磷酸化； 4)M受体与cAMP抑制的偶联 钙通道磷酸化的蓄积和抑制不同 房室之间的关系以及生理效应是否 由于抑制cAMP的形成在心房和心脏之间存在差异 5)蛋白激酶C的心脏生理功能之一 是调节对β-肾上腺素能和毒扁豆碱的生理反应 胆碱能激动剂通过磷酸化其各自的受体或其 各自的GTP结合蛋白。这些研究应该会增强我们的 胆碱能-肾上腺素能相互作用的分子基础 在调节心脏的变力和变时状态中，应该 提供对布雷迪诱因的重要事件的见解-以及 快速性心律失常。

The main objective is to investigate the role of cardiac phosphoproteins in the modulation of cardiac function and excitability. These studies are proposed to test the hypotheses that cardiac phosphoproteins modulate cardiac function by mediating changes in calcium and potassium permeability as well as in the force and rate of contraction and that the phosphoproteins serve as the locus of interaction between beta-adrenergic and muscarinic cholinergic inputs to the heart. The proposed studies will use monolayer heart cells cultured from embryonic chick heart, which provide the advantage of permitting measurement at intervals as short as five seconds and hence the ability to obtain accurate time course analysis. The specific goals of these studies are to determine whether: 1) a subunit of the cardiac calcium channel becomes phosphorylated in response to isoproterenol and mediates the increase in calcium influx (measured as 45Ca++ influx rate) and contractility; 2) a close correlation exists between the time course of appearance of the phosphorylation of calcium channel subunit and other phosphoproteins (protein C and phospholamban) and that of development of the respective physiologic responses and whether a close correlation also exists between the time course of reversal of the phosphorylation of these proteins and that of reversal of the respective physiologic responses; 3) the muscarinic agonist carbachol antagonizes isoproterenol-stimulated physiologic responses by dephosphorylating the calcium channel subunit, phospholamban and protein C; 4) the coupling of muscarinic receptor to the inhibition of cAMP accumulation and the inhibition of calcium channel phosphorylation differs between the atria and the ventricle and whether the physiologic effects caused by the inhibition of cAMP formation differ between the atria and the ventricle; 5) one of the cardiac physiologic functions of protein kinase C is to modulate the physiologic responses to beta-adrenergic and muscarinic cholinergic agonists by phosphorylating its respective receptors or its respective GTP-binding proteins. These studies should enhance our understanding of the molecular basis of cholinergic-adrenergic interaction in modulating the inotropic and chronotropic state in the heart and should provide insights into the events important in predisposing to brady-and tachyarrhythmia.