CATECHOLAMINES AND HYPERTROPHY OF CULTURED HEART CELLS

什么调节心肌肥厚是一个根本性的问题 心血管疾病的重要性，是我工作的长期目标。 在过去的三年里，我开发了一种新的方法来解决这个问题， 使用新生大鼠心肌细胞（MC）的纯培养物， 分化并且不增殖（Circ Res 50：101-116，1982）。 我有 表明这些MC通过肥大生长，这一过程受 血清和儿茶酚胺（CircRes，出版中）。 在这项研究中， 去甲肾上腺素（NE）的肥大作用不被阻断， β-肾上腺素能拮抗剂普萘洛尔 我最近发现， NE的作用被α-肾上腺素能拮抗剂酚妥拉明阻断。 这和其他证据强烈表明，MC肥大诱导 在无血清培养物中由NE引起的免疫应答是α-肾上腺素能应答。 进一步 对这一新颖而重要的发现的描述是本书的重点。 目前的工作。 这项工作将测试以下想法：Ne和EPI 心肌生长因子的作用类似于其他生长因子， 其肥大效应是一种α-肾上腺素能反应; 肥大是独立于任何刺激的跳动，这可能是 主要是β-肾上腺素能反应;有效浓度 NE和EPI的生理相关性; 培养与体内MC肥大具有共同的特征。 具体 问题将包括以下内容： α-肾上腺素能受体; NE浓度、暴露持续时间和 诱导肥大所必需的可能摄取;生长与 跳动;肌球蛋白积累的比例增加， 肥大;最大肥大和消退; NE诱导 内源性营养因子;环核苷酸和 α-肾上腺素能受体;以及与其他α-相关 激素、细胞外钙和细胞伸展。 类似的研究将 与另一种活性的儿茶酚胺肾上腺素（EPI）一起使用。 我会用 具有90% MC的定义的无血清培养物;一个既定的实验 方案;我发表的细胞大小（蛋白质、体积和表面）方法 面积）;以及肌球蛋白（SDS-PAGE），儿茶酚胺（放射酶）， 环核苷酸（放射免疫测定法）和α-肾上腺素能受体 （放射性配体结合）。 心肌α受体的作用尚不清楚。 虽然没有预期它们介导肥大效应， 数据与这种可能性是一致的。 这项工作将提供新的 对MC α反应以及NE和EPI作为生长因子的观点， 培养的MC。

What regulates myocardial hypertrophy is a problem of fundamental importance in cardiovascular disease and is the long-range aim of my work. Over the past three years I have developed a new approach to this problem, using pure cultures of neonatal rat myocardial cells (MCs) which are differentiated and do not proliferate (Circ Res 50:101-116, 1982). I have shown that these MCs grow by hypertrophy, a process that is regulated by serum and by catecholamines (Circ Res, in press). In that study, the hypertrophic effect of norepinephrine (NE) was not blocked by the beta-adrenergic antagonist, propranolol. I have found recently that the effect of NE is blocked by the alpha-adrenergic antagonist, phentolamine. This and other evidence strongly suggests that the MC hypertrophy induced by NE in serum-free cultures is an alpha-adrenegic response. Further characterization of this novel and important finding is the focus of the present work. This work will test the following ideas: that Ne and EPI are myocardial growth factors with actions analagous to other growth factors; that their hypertrophic effect is an alpha-adrenergic response; that hypertrophy is independent of any stimulation of beating, which may be predominantly a beta-adrenergic response; that the effective concentrations of NE and EPI are physiologically relevant; and that MC hypertrophy in culture shares characteristics with MC hypertrophy in vivo. Specific questions will include the following: the subspecificity of the alpha-adrenergic receptor; NE concentration, exposure duration, and possible uptake necessary to induce hypertrophy; the relation of growth to beating; the proportionate increase in myosin accumulation during hypertrophy; maximum hypertrophy and regression; the induction by NE of endogenous trophic factors; changes in cyclic nucleotides and alpha-adrenergic receptors; and interactions with other alpha-related hormones, extracellular calcium, and cell stretch. Similar studies will be done with the other active catecholamine, epinephrine (EPI). I will use defined, serum-free cultures with 90% MCs; an established experimental protocol; my published methods for cell size (protein, volume, and surface area); and assays for myosin (SDS-PAGE), catecholamines (radioenzymatic), cyclic nucleotides (radioimmunoassay), and alpha-adrenergic receptors (radioligand binding). The role of myocardial alpha receptors is unclear. It has not been expected that they mediate a hypertrophic effect, although the data is consistent with this possibility. This work will provide new perspectives on MC alpha responses and on NE and EPI as growth factors in cultured MCs.