MECHANISMS OF SIGNAL TRANSDUCTION OF CARDIAC OPIOID RECEPTOR STIMULATION

心脏阿片受体刺激的信号传导机制

• 批准号: 3745558
• 负责人: S PEPE
• 金额: --
• 依托单位: NATIONAL INSTITUTE ON AGING
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3745558
• 关键词: adenylate cyclase; biological signal transduction; calcium channel; calcium flux; catecholamines; cyclic AMP; enkephalins; enzyme activity; heart pharmacology; inositol phosphates; laboratory rat; leucine; muscle cells; norepinephrine; opioid receptor; phospholipase C; receptor coupling

It has been found that cardiac myocytes produce and secrete opioids and hav opioid peptide receptors (OPR). We have previously shown that the k OPR agonist, leucine-enkephalin (LE), specifically reduces twitch, cytosolic Ca2+ transient (Cai) and L-type Ca2+ channel current amplitude in adult rat ventricular myocytes. As it has been shown that opioid peptides are coreleased with catecholamines from autonomic nerve endings within the heart, we propose that OPR stimulation interacts with beta-adrenergic receptor (beta-AR) stimulation in a negative feedback role. Although it has been reported that OPR stimulation effects involve increased phospholipase C activity and thus IP3 formation, OPR stimulation also may decrease cardia cAMP levels. In contrast, beta-AR stimulation by norepinephrine (NE) elevates basal cAMP levels. In an isolated heart preparation peak developed pressure was increased to 217% of control by NE (10-7M), addition of LE (10 8M) resulted in a marked reduction in developed pressure to 66% of control within 15-25min. Further addition of the OPR antagonist naloxone (10-8M) to the LE+NE buffer rapidly reversed the LE effect (<1-2min) to 188% of contro systolic pressure. LE alone at 10-8M had no significant effect on developed pressure but was highly potent following NE. A non-hydrolyzable analog of cAMP, CPTcAMP, at 3x10-5M increased peak developed pressure to 176% of control but LE (10-8M) +CPTcAMP had no significant effect on peak pressure. Additional experiments were performed in single rat ventricular myocytes where cytosolic Ca2+ transient and contraction amplitude were measured during an identical series of experiments. Results from these experiments support those obtained with the isolated heart preparation. These results indicate that there is a distinct interaction of OPR and beta-AR stimulatio at the postsynaptic level which may alter receptor coupling to adenylate cyclase or inactivate adenylate cyclase itself. Further elucidation of this opioid signal transduction mechanism may shed light on an important negativ feedback control beta-adrenergic cardiac effects.

已经发现心肌细胞产生和分泌阿片样物质， 阿片肽受体（OPR）。我们之前已经证明，k OPR 激动剂，亮氨酸脑啡肽（LE），特异性减少抽搐，胞质 成年大鼠Ca 2+瞬变（Cai）和L-型钙通道电流幅度 心室肌细胞因为已经表明阿片肽是 与来自自主神经末梢的儿茶酚胺共同释放， 心脏，我们认为OPR刺激与β-肾上腺素能相互作用 受体（β-AR）刺激负反馈作用。虽然 据报道，OPR刺激效应涉及增加磷脂酶 C活性，从而IP 3的形成，OPR刺激也可能减少贲门 cAMP水平。相反，去甲肾上腺素（NE）刺激β-AR 提高基础cAMP水平。在离体心脏制备中， NE（10 ~（-7）M）、LE（10 8 M）导致显着降低开发压力的66%的控制 在15- 25分钟内。将OPR拮抗剂纳洛酮（10- 8 M）进一步添加至 LE+NE缓冲液可迅速逆转LE的作用（<1- 2 min），为对照组的188%。 收缩压LE单独在10- 8 M时对发育的 压力，但在NE之后非常有效。的不可水解类似物， cAMP，CPTcAMP，在3 × 10 - 5 M时，使峰发展压力增加至176%， LE（10 ~（-8）M）+CPTcAMP对峰压无明显影响。 在单个大鼠心室肌细胞中进行了额外的实验 其中测量胞质Ca 2+瞬变和收缩幅度 在一系列相同的实验中。这些实验的结果 支持用离体心脏制备获得的那些。这些结果 表明OPR和β-AR刺激之间存在明显相互作用， 在突触后水平，这可能会改变受体与腺苷酸的偶联 环化酶或腺苷酸环化酶本身。进一步阐明这一点 阿片信号转导机制可能揭示了一个重要的负性， 反馈控制β-肾上腺素能心脏效应。