MYOCARDIAL PROTEIN KINASE C & B-ADRENOCEPTORS IN CHF

蛋白激酶C，一种钙和磷脂依赖性蛋白 磷酸化酶，存在于心肌，已被证明 最近通过以下方法诱导心脏β-肾上腺素能脱敏 β-肾上腺素受体的磷酸化。 研究激活是否 蛋白激酶C负责心脏β-肾上腺素能 在充血性心力衰竭的脱敏，我们建议1） 比较心肌肌膜蛋白的数量和/或活性 激酶C在心力衰竭和假手术狗，2） 表征蛋白激酶C催化的磷酸化 心肌内源性底物蛋白 失败和假手术的狗，3）研究的影响， 充血性心力衰竭对蛋白激酶C介导的细胞凋亡的影响 功能在体外，使用分离的肌细胞制剂，4）， 确定蛋白激酶C的变化是否仅发生在 右心室压力超负荷（心室特异性）或 也见于左心室和循环淋巴细胞， 5)研究是否抑制蛋白激酶C在体内 使心肌β受体密度、腺苷酸环化酶正常化 活动和β-肾上腺素能反应性。 充血性右心衰竭会由三尖瓣产生 撕脱和进行性肺动脉收缩。 将进行血流动力学测量以表征 在动物被处死之前，心脏衰竭。 内在 收缩功能和正性肌力反应 心室β受体激动剂将被研究，使用一个孤立的权利 心室乳头肌制备。 采集样品 从右心室和左心室测量（3 H）-佛波醇- 12，13-二丁酸结合，蛋白激酶C活性，蛋白激酶 内源性底物蛋白的C-催化磷酸化，β- 受体密度和腺苷酸环化酶活性。 离体肌细胞 制备将用于研究蛋白激酶的影响， 充血性心力衰竭对细胞内 氢和钙浓度，使用荧光指示剂 和荧光分光光度法。 这项研究结合了生理， 在有意识的动物模型中进行生物化学和细胞测量。 这种综合性的研究不仅有助于我们进一步了解 导致细胞内蛋白质含量下降的基本细胞机制 心脏对交感神经刺激的敏感性 心力衰竭，但也可能为我们提供一种新的模式， 充血性心力衰竭的治疗。

Protein kinase C, a Ca2+- and phospholipid-dependent protein phosphorylation enzyme present in myocardium, has been shown recently to induce cardiac beta-adrenergic desensitization by phosphorylation of beta-adrenoceptors. To study whether activation of protein kinase C is responsible for cardiac beta-adrenergic desensitization in congestive heart failure, we propose 1) to compare the number and/or activity of cardiac sarcolemmal protein kinase C in heart failure and sham-operated dogs, 2) to characterize the protein kinase C-catalyzed phosphorylation of endogenous substrate proteins in the myocardium of the heart failure and sham-operated dogs, 3) to study the effect of congestive heart failure on protein kinase C-mediated cellular functions in vitro, using isolated myocyte preparations, 4) to determine whether changes in protein kinase C occur only in the pressure-overloaded right ventricle (chamber-specific) or they are also found in the left ventricle and circulating lymphocytes, and 5) to study whether inhibition of protein kinase C in vivo normalizes myocardial beta-receptor density, adenylate cyclase activity and beta-adrenergic responsiveness in heart failure dogs. Congestive right heart failure will be produced by tricuspid avulsion and progressive pulmonary artery constriction in dogs. Hemodynamic measurements will be taken to characterize the degree of heart failure before the animals are sacrificed. Intrinsic contractile function and inotropic responsiveness of the right ventricle to beta-agonists will be studied, using an isolated right ventricular papillary muscle preparation. Samples will be taken from the right and left ventricles for measuring (3H)-phorbol- 12,13-dibutyrate binding, protein kinase C activity, protein kinase C-catalyze phosphorylation of endogenous substrate proteins, beta- receptor density and adenylate cyclase activity. Isolated myocyte preparations will be used to study the effects of protein kinase C as influenced by congestive heart failure on intracellular hydrogen and calcium concentrations, using fluorescent indicators and spectrofluorimetry. The study incorporates physiological, biochemical and cellular measurements in a conscious animal model. This integrative study will not only further our understanding of the fundamental cellular mechanisms responsible for the decreased sensitivity of the heart to sympathetic stimulation in congestive heart failure, but also may provide us a new modality for the treatment of congestive heart failure.