ANDROGENIC AND ADRENERGIC ACTIONS ON HEART MYOCYTES

对心肌细胞的雄激素和肾上腺素作用

基本信息

批准号：
3338749
负责人：
HAROLD KOENIG
金额：
$ 9.9万
依托单位：
NORTHWESTERN UNIVERSITY AT CHICAGO
依托单位国家：
美国
项目类别：
财政年份：
1982
资助国家：
美国
起止时间：
1982-01-01 至 1988-09-14
项目状态：
已结题

项目摘要

We will contiune studies on the molecular and cellular mechanisms of androgenic and Beta-adrenergic responses in heart myocytes. Previous studies in rodent kidney cortex and heart, using tissue slices, revealed that nanomolar concentrations of testosterone and 1-isoproterenol induce a rapid (less the 1 min) Ca2+ - and receptor-dependent stimulation of Ca2+ fluxes, endocytosis and transport of hexose and amino acid; and an early stimulation of ornithine decarboxylase (ODC) activity and polyamine synthesis. Studies with the ODC inhibitor Alpha-difluoromethylornithine (DFMO) showed that rapid stiumulation of ODC activity and polyamine synthesis is obligatory for androgenic and Beta-adrenergic stimulation of Ca2+ fluxes and membrane transport processes. On the basis of these and other findings a new model for signal transduction and stimulus-response (permeability) was proposed in which stimulaltion of ODC activity and polyamine synthesis plays a pivotal role in regulating Ca2+ fluxes. In this model, activation of cell surfar receptors induces an early, transient, Ca2+ - (or Ca2+ -calmodulin), prostaglandin- and cyclic AMP-dependent stimulation of the catalytic activity of a cryptic ODC in or near the plasma membrane by a phosphorylation-dephosphorylation sequence involving ODC (or possibly an ODC regulatory protein). The delayed increase in ODC activity results from an induction of new ODC protein. Newly synthesized polyamines serve as messengers to generate a Ca2+ signal by increasing Ca influx or mobilizing intracellular Ca, or both, via a cation exchange reaction. Polyamines are thought to be involved in the regulation of membrane transport, cytoskeletal, mitochondrial, lysosomal function, and other cell responses by: (a) generating local Ca2+ signals, and mediating Ca2+ -dependent processes; and (b) binding to cytomembranes and other components with acidic sites and inducing conformational changes by displacing bound Ca or decreasing surface charge density. The specific aims of this project are to study in testosterone- and isoproterenol-stimulated Langendorff-perfused rat heart and acutely isolated cardiac myocytes: (1) Positive inotropic effects and their polyamine dependence. (2) Conversion of phosphorylase b to phosphorylase a and glycogenolysis. (3) Changes in Ca2+ fluxes and free cytosolic Ca2+ concentration and their polyamine dependence. (4) Changes in Na22+ transport, Rb86+ transport and intracellular pH and their polyamine dependence. (5) The molecular and cellular mechanisms underlying the rapid stimulation of ODC activity. (6) Ca-dependent effects of the cardiac glycosides digoxin and ouabain, and the antiarrythmogenic drug phenytoin and the role of polyamine synthesis of their effects.

我们将讨论有关分子和细胞机制的研究心肌细胞中的雄激素和β-肾上腺素能反应。以前的使用组织切片中的啮齿动物肾皮质和心脏的研究显示纳摩尔浓度的睾丸激素和1-异丙肾上腺素诱导A 快速（1分钟）Ca2+ - 和受体依赖性刺激Ca2+ 通量，内吞作用以及己糖和氨基酸的转运；和早鸟嘌呤脱羧酶（ODC）活性和多胺刺激合成。 ODC抑制剂α-二氟甲基氨酸的研究（DFMO）表明ODC活性和多胺的快速划分合成对于雄激素和β-肾上腺素能刺激是必不可少的 CA2+通量和膜运输过程。根据这些和其他发现是一种新的信号转导和刺激反应的模型提出（渗透性），其中ODC活性的刺激和多胺合成在调节Ca2+通量中起关键作用。在该模型，细胞表面受体的激活诱导早期，瞬态，Ca2+ - （或Ca2+ -calmodulin），前列腺素和周期性 AMP依赖性刺激对或通过磷酸化 - 二磷酸化序列靠近质膜涉及ODC（或可能是ODC调节蛋白）。延迟 ODC活性的增加导致诱导新的ODC蛋白。新合成的多胺作为使CA2+信号的使者通过增加CA流入或通过A动员细胞内CA或两者兼而有之阳离子交换反应。多胺被认为参与了调节膜转运，细胞骨架，线粒体，溶酶体的调节功能和其他单元格响应：（a）生成本地CA2+信号，并介导Ca2+依赖性过程；（b）与细胞膜结合以及具有酸性位点并诱导构象变化的其他组件通过取代结合的CA或降低表面电荷密度。具体该项目的目的是研究睾丸激素 - 和异丙肾上腺素刺激的langendorff垂直的大鼠心脏敏锐孤立的心肌细胞：（1）阳性肌力作用及其多胺依赖性。（2）将磷酸化酶B转换为磷酸化酶A 和糖原分解。（3）CA2+通量和游离胞质CA2+的变化浓度及其多胺依赖性。（4）NA22+的变化运输，RB86+传输和细胞内pH及其多胺依赖。（5）快速的分子和细胞机制 ODC活性的刺激。（6）心脏的CA依赖性作用糖苷二高氧蛋白和瓦巴因，以及抗乳腺癌药物苯二甲酸酯以及多胺合成其作用的作用。