DIVERSITY OF A1-ADRENERGIC SIGNALING PATHWAYS IN HEART

α 1-肾上腺素能信号转导通路在糖尿病中的重要性 心肌通过它们对细胞生长的调节作用来证明 （肥大）、收缩性、变时性和能量代谢。 目的 这一建议的目的是确定alpha 1- 肾上腺素能信号转导途径，调节肥大和 培养的新生心肌细胞的变时性。的优势 使用培养的心肌细胞进行这些研究， 这些细胞在无血清培养基中维持数天， 并进行显微注射或转染， 信号转导中特定步骤的实验操作 通路具体而言，本提案将寻求： α 1-肾上腺素能受体、G蛋白的数量、类型和丰度， 心肌细胞中磷脂酶C亚型; 2）确定 各种α 1-肾上腺素能受体亚型在 介导肥大和变时性反应; 3）确定 特异性G蛋白在偶联不同的α 1-肾上腺素能 受体亚型的肥大和变时性反应; 4）， 确定Ins 1，4，5-P3和二酰基甘油是否是针对以下的差异信号： 肥大和变时性;和5）确定的分子基础， 心脏发育过程中α 1-肾上腺素能反应性的变化。 实验方法将首先确定潜在的蛋白质 参与α 1-肾上腺素能信号转导途径， 然后通过显微注射或注射基因来扰乱这一通路 编码这些蛋白质或蛋白质本身，并确定 这种扰动对α 1-肾上腺素能介导肥大细胞的影响 和变时性反应。将通过以下方法评估肥大性生长： 监测心房肌特异性标记基因或蛋白质的诱导 天然因子和肌球蛋白轻链-2。Chronotropy将是 通过监测心跳到心跳Ca 2+瞬变与 荧光指示剂染料Fura 2。 预期从拟议研究中获得的信息将开始， 阐明了α 1- 肾上腺素能受体介导的心肌效应 发展

The importance of alpha1-adrenergic signal transduction pathways in cardiac muscle is demonstrated by their regulatory effects on cell growth (hypertrophy), contractility, chronotropy and energy metabolism. The aim of this proposal is to determine the proximal steps in the alpha1- adrenergic signal transduction pathways that modulate hypertrophy and chronotropy in cultured, neonatal cardiac myocytes. The advantages in using cultured, cardiac myocytes for these studies include the ability of these cells to be maintained in serum-free medium for several days, and to undergo microinjection or transfection, allowing direct experimental manipulation of specific steps in the signal transduction pathway. Specifically, this proposal will seek: l) to determine the number, type and abundance of alpha1-adrenergic receptor, G protein, and phospholipase C subtypes in cardiac muscle cells; 2) to determine the contribution of the various alpha1-adrenergic receptor subtypes in mediating hypertrophic and chronotropic responses; 3) to determine the role of specific G protein(s) in coupling the distinct alpha1-adrenergic receptor subtypes to the hypertrophic and chronotropic responses; 4) to determine if Ins l,4,5-P3 and diacylglycerol are differential signals for hypertrophy and chronotropy; and 5) to determine the molecular basis for changes in alpha1-adrenergic responsiveness during cardiac development. The experimental approach will be to first identify potential proteins involved in the alpha1-adrenergic signaling transduction pathway, and then to perturb the pathway, by microinjecting or transfecting genes encoding these proteins or the proteins themselves, and determining the effect of this perturbation on alpha1-adrenergic-mediated hypertrophic and chronotropic responses. Hypertrophic growth will be assessed by monitoring the induction of specific marker genes or proteins for atrial naturietic factor and myosin light chain-2. Chronotropy will be determined by monitoring the beat-to-beat Ca2+ transients with the fluorescent indicator dye fura 2. The information expected from the proposed studies will begin to elucidate the molecular basis underlying the diversity of alpha1- adrenergic receptor-mediated effects in cardiac muscle during development.