METABOLIC AND HORMONAL CONTROL OF CARDIAC CONTRACTION

在这笔赠款的最后三年里，我们发现变力作用 β-肾上腺素能激动剂的作用由分离和解离组成 肌膜钙通量和肌浆网功能的变化 网状钙滞留。零钠溶液消除了 异丙肾上腺素的正性肌力作用，慢刺激 内向钙电流并明显降低细胞内循环升高 AMP不改变异丙肾上腺素的松弛作用 张力峰发展的时间。我们最近在 低本底、高亲和力可逆性和不可逆性研究进展 β-肾上腺素能受体的探针和投射的附加高 分子量、电子密度和荧光探针应有助于 β-肾上腺素能受体及其受体的功能和解剖定位 心肌中产生环磷酸腺苷的部位。最初的观察 通过这个实验室，RNA和蛋白质合成抑制剂阻止了 儿茶酚胺耐受性将成为机制研究的重点。 儿茶酚胺的耐受性。人们普遍证实，RNA 和蛋白质合成参与了多种不稳定因素 细胞类型和荷尔蒙。而环化酶可以被分离出来，这表明 耐火性，数量方面只反映了一小部分 异丙肾上腺素的急剧增加刺激了循环AMP的积累和 随后在整个细胞中观察到不稳定。正因为如此，急性 细胞融合实验已经启动，并已经证明 将改变的反应性从一个细胞迅速转移到 下一首。这项技术将用于鉴定和分离因子(S) 这赋予了它难以捉摸的感觉。在这方面还提出了更多的实验 补充申请，以进一步评估我们最近的调查结果 异丙肾上腺素或霍乱毒素对培养细胞的长期处理 结果环磷酸腺苷介导的β-肾上腺素能受体结合丧失 网站。CAMP介导的受体丢失的机制将是 研究以确定环状AMP是否减少受体合成或 通过对受体的某些共价修饰来修饰受体结合。

During the last three years of this grant we discovered that the inotropic action of Beta-adrenergic agonists consists of separate and dissociable functional alterations of sarcolemmal calcium flux and sarcoplasmic reticulum calcium sequestration. Zero sodium solutions eliminate the positive inotropic action of isoproterenol, the stimulation of the slow inward calcium current and markedly reduce the rise in intracellular cyclic AMP without altering the relaxant effect of isoproterenol which decreases the time for peak tension development. Our recent success in the development of low background, high affinity reversible and irreversible probes for the Beta-adrenergic receptor and projected additional high molecular weight, electron dense and fluorescent probes should facilitate the functional and anatomical localization of Beta-adrenergic receptors and sites of cyclic AMP generation in the myocardium. The original observation by this laboratory that RNA and protein synthesis inhibitors prevent catecholamine refractoriness will be a focus for studies of the mechanism of catecholamine refractoriness. There is widespread confirmation that RNA and protein synthesis are involved in refractoriness in a wide variety of cell types and hormones. While cyclase can be isolated which shows some refractoriness, the quantitative aspects reflect only a fraction of the dramatic rise in isoproterenol stimulated cyclic AMP accumulation and subsequent refractoriness observed in whole cells. Because of this, acute cell fusion experiments have been initiated and have already demonstrated the ability to acutely transfer altered responsiveness from one cell to the next. This technique will be used to identify and isolate the factor(s) which impart refractoriness. Additional experiments are proposed in this supplemental application to further evaluate our recent finding that long term treatment of cultured cells with isoproterenol or cholera toxin results in a cyclic AMP mediated loss of Beta-adrenergic receptor binding sites. The mechanism of cyclic AMP mediated receptor loss will be investigated to determine if cyclic AMP reduces receptor synthesis or modifies receptor binding by some covalent modification of the receptor.