ADENOSINE RECEPTORS IN THE DIGESTIVE TRACT

这是一个修订后的建议，研究腺苷受体在 小肠 该项目旨在测试一般假设 腺苷调节神经元活动和递质释放， 与肌间质上的受体的异质群体相互作用 可能与腺苷酸环化酶/cAMP系统偶联的神经元。 的 该项目将使用电生理学和生物化学方法，以及 肠突触体，以研究腺苷能信息的转导， 肌间神经丛和神经节的显微解剖 准备工作 该项目旨在将受体亚型分类 其调节AH/2型和S/1型神经元的突触活性。 这些受体与腺苷酸环化酶的偶联将在 新型蛋白激酶A的cAMP依赖性调节研究 激动剂/拮抗剂对Sp-腺苷-3 '-5'-环单硫代磷酸酯 （cAMPs）/Rp-cAMPs，百日咳毒素，特异性cAMP依赖性 磷酸二酯酶抑制剂，环化酶抑制剂MDL 12，330 A，垂体 腺苷酸环化酶激活多肽和cAMP测量 分离的肌间神经节 磷酸肌醇/蛋白质的作用 腺苷能反应中的激酶C系统将用蛋白质 激酶C刺激剂和抑制剂。 动作电位时程 AH/2型神经元将作为模型系统来研究对 钙内流 只有AH/2型神经元具有染色体的假设 腺苷受体将在比较形态学的研究中进行测试， 电生理学和对腺苷的反应。 内源性腺苷可能 对肌间神经元的活动施加紧张性抑制性张力， 参与的受体可能与AH/2型神经元中的腺苷酸环化酶有关。 这一假设将通过旨在阻断 内源性腺苷的作用。 AH/2型中的缓慢突触兴奋 神经元被认为是通过激活cAMP第二 信使系统 拟议的研究将表征腺苷 参与抑制5-HT介导的慢兴奋性 突触后电位（慢EPSP），在AH/2型神经元中引起， 神经节间连接的局部刺激。 抑制内源 将在分离的神经节中研究嘌呤能激动剂的5-HT释放， 肠突触体 整合这些独特模型的数据 系统，将阐明腺苷在肌间 神经元 神经元缺氧的模型也将提供对神经元缺氧的深入了解。 内源性腺苷抑制神经传递的机制 肠道的病理状态，如局部缺血和炎症。

This is a revised proposal for investigation of adenosine receptors in the small intestine. The project is intended to test the general hypothesis that adenosine modulates neuronal activity and transmitter release by interacting with a heterogeneous population of receptors on myenteric neurons that may be coupled to the adenylate cyclase/cAMP system. The project will use electrophysiological and biochemical methods as well as enteric synaptosomes to study the transduction of adenosinergic messages in microdissected myenteric plexus and enzymatically dissociated ganglion preparations. The project is designed to classify the receptor subtypes which modulate the synaptic activity of AH/type 2 and S/type 1 neurons. The coupling of these receptors to adenylate cyclase will be tested in cAMP-dependent modulation studies with the novel protein kinase A agonist/antagonist pair Sp-adenosine-3'-5'-cyclomonophosphothioate (cAMPs)/Rp-cAMPs, pertussis toxin, specific cAMP-dependent phosphodiesterase inhibitors, the cyclase inhibitor MDL 12,330A, pituitary adenylate cyclase-activating polypeptide and cAMP measurements in dissociated myenteric ganglia. The role of the phosphoinositide/protein kinase C system in adenosinergic responses will be studied with protein kinase C stimulators and inhibitors. The action potential duration in AH/type 2 neurons will serve as a model system to study direct effects on calcium influx. The hypothesis that only AH/type 2 neurons possess somal adenosine receptors will be tested in studies that compare the morphology, electrophysiology and responses to adenosine. Endogenous adenosine may exert a tonic inhibitory tone on activity of myenteric neurons and the receptors involved may be linked to adenylate cyclase in AH/type 2 neurons. This hypothesis will be tested with interventions intended to block the actions of endogenous adenosine. Slow synaptic excitation in AH/type 2 neurons is believed to occur through activation of the cAMP second messenger system. The proposed studies will characterize the adenosine receptors that are involved in suppression of 5-HT-mediated slow excitatory postsynaptic potentials (slow EPSPs), elicited in AH/type 2 neurons by focal stimulation of interganglionic connectives. Inhibition of endogenous 5-HT release by purinergic agonists will be studied in isolated ganglia and enteric synaptosomes. Integration of the data from these unique model systems, will clarify the signaling mechanisms for adenosine in myenteric neurons. A model of neuronal hypoxia will also provide insight into the mechanisms by which endogenous adenosine suppresses neurotransmission in pathologic states of the gut such as ischemia and inflammation.