DEVELOPMENTAL REGULATION OF MAMMALIAN CARDIAC CELLS

哺乳动物心肌细胞的发育调节

基本信息

批准号：
2685402
负责人：
RONALD W JOYNER
金额：
$ 27.06万
依托单位：
EMORY UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
1995
资助国家：
美国
起止时间：
1995-04-01 至 1999-12-31
项目状态：
已结题

项目摘要

The specific goal for this project is to understand the developmental differences in properties and adrenergic regulation of Ca2+ current density (I(Ca), pA/pF) in the rabbit heart. Differences between adult and newborn cells may be due to differences at the level of the number and types of receptors, the amount and type of G proteins, the amount and type of adenylyl cyclase, the amounts and types of phosphodiesterases, phosphatases, kinases or other aspects of the Ca2+ current modulatory pathway. We will test specific hypotheses related to developmental differences in competitive interaction of kinases and phosphatase enzymes on adrenergic regulation of Ca2+ current. Our first hypothesis is that: Inhibition of PPase in newborn has greater effect due to a greater PPase activity and different PPase types in NB cells. We will evaluate the developmental changes in the activity of specific kinases and PPases both in the basal state and with stimulation via the cAMP pathway. Specific tests will be done concerning the role of protein kinase A and other kinases in regulating the basal current magnitude, in specific types of PPases involved in dephosphorylation of Ca2+ channels, and in the dual action of cAMP in regards to enhancing kinase activity and inhibiting PPase activity as a means of increasing the availability of Ca2+ channels. Our second hypothesis is that: The multiple sites of phosphorylation that regulate availability and gating mode of Ca2+ channels are differentially phosphorylated in newborn and adult cells. Single channel studies with both kinase and PPase inhibitors will be used to specifically test hypotheses relating to the mode changes of Ca2+ channel opening as determined by the actions of kinases and PPases. Our third hypothesis is that: differences in the distribution of specific isoforms of inhibitory G proteins and differences in specific isoforms of adenylyl cyclase provide a mechanism for the greater inhibitory effects of carbachol in NB than in AD cells and also the differential effects of adenosine compared to carbachol in the inhibition of the stimulation of I(Ca) by isoproterenol and forskolin. We will expand the time frame over which we study these developmental differences by studies of I(Ca) amplitude and modulation to fetal heart cells. These studies will be important in clarifying the biochemical basis of the developmental changes we observe, with specific emphasis on developmental changes in the expression and function of phosphatase enzymes. Our proposal is the first comprehensive evaluation of developmental changes in mammalian cardiac ionic current magnitude and adrenergic regulation. Ca2+ currents play major roles in controlling the action potential duration as well as the supply of Ca2+ to control contractility. The proposed studies will contribute toward our goal of improving the treatment of cardiac dysfunction in infants and children.

该项目的具体目标是了解发育 Ca2+ 电流的特性和肾上腺素能调节差异兔心脏密度（I(Ca)、pA/pF）。成人与成人的区别新生细胞可能是由于数量和水平上的差异受体的类型、G 蛋白的数量和类型、数量和类型腺苷酸环化酶、磷酸二酯酶的量和类型，磷酸酶、激酶或 Ca2+ 电流调节的其他方面途径。我们将测试与发育相关的具体假设激酶和磷酸酶竞争性相互作用的差异 Ca2+ 电流的肾上腺素调节。我们的第一个假设是：由于 PPase 含量较高，对新生儿 PPase 的抑制作用更大 NB细胞中的活性和不同的PPase类型。我们将评估特定激酶和 PPase 活性的发育变化处于基础状态并通过 cAMP 途径进行刺激。具体的将进行有关蛋白激酶 A 和其他作用的测试调节基础电流大小的激酶，在特定类型中 PPase 参与 Ca2+ 通道的去磷酸化，并在双重作用中发挥作用 cAMP 在增强激酶活性和抑制激酶活性方面的作用 PPase 活性是增加 Ca2+ 通道可用性的一种手段。我们的第二个假设是：多个磷酸化位点 Ca2+通道的调节可用性和门控模式是不同的在新生儿和成人细胞中磷酸化。单通道研究激酶和PPase抑制剂都将用于专门测试与 Ca2+ 通道开放模式变化相关的假设为由激酶和 Pase 的作用决定。我们的第三个假设是即：特定抑制亚型分布的差异 G 蛋白和腺苷酸环化酶特定亚型的差异提供了一种机制，使卡巴胆碱在 NB 中具有更大的抑制作用与 AD 细胞相比，以及腺苷的不同作用相比卡巴胆碱抑制 I(Ca) 的刺激异丙肾上腺素和毛喉素。我们将扩大我们的时间框架通过研究 I(Ca) 幅度和对胎儿心脏细胞的调节。这些研究将在以下方面发挥重要作用：阐明我们观察到的发育变化的生化基础，特别强调表达和表达的发展变化磷酸酶的功能。我们的建议是第一个全面的哺乳动物心脏离子电流发育变化的评估幅度和肾上腺素能调节。 Ca2+电流在控制动作电位持续时间以及 Ca2+ 的供应控制收缩力。拟议的研究将有助于我们改善婴儿心功能障碍的治疗目标孩子们。