CATECHOLAMINE RELEASE IN THE HEART

拟议项目的总体目标是了解控制 交感神经系统对心脏的影响，重点是 涉及对解放和消散进行管制的进程 神经递质。心脏对交感神经活动的反应 部分依赖于去甲肾上腺素(NE)在体内的浓度 神经效应器间隙，而这又取决于NE释放和 移走。在这个授权期内，主要的重点将是界定 某些物理过程(扩散和散装运输)的作用 与东北方向的消散有关。研究将在#年进行。 麻醉的开胸狗。我们会刺激心脏的交感神经 神经，并将测量变色和变力反应 心脏和冠状静脉窦血中去甲肾上腺素的充盈率。这些 将在有无可卡因的情况下进行观察。完成 将产生心脏传导阻滞，因此心率可以在一个小时内变化 通过人工起搏，范围很广。扩散对生物多样性的影响 去甲肾上腺素的消散将通过改变冠脉血流量来确定 流。散装运输的影响，归因于按摩的作用 跳动的心脏，将通过分别改变频率来确定 以及心脏收缩的强度。我们还将继续我们的 去甲肾上腺素神经元释放调控因素的研究， 尤其是心脏中腺苷的突触前效应。我们会 测定外源性和内源性腺苷对心脏的影响 交感神经刺激的反应和去甲肾上腺素的相关频率 溢出到冠状静脉窦血液中。

The overall objective of the proposed project is to understand the control of the heart by the sympathetic nervous system, with emphasis on the processes involved in the regulation of the liberation and dissipation of the neurotransmitter. The cardiac responses to sympathetic neural activity depend in part on the concentration of norepinephrine (NE) in the neuroeffector gaps, which in turn depends on the rates of NE release and removal. In this grant period, the major emphasis will be to define the roles of some of the physical processes (diffusion and bulk transport) involved in the dissipation of NE. Studies will be carried out in anesthetized, open-chest dogs. We will stimulate the cardiac sympathetic nerves, and will measure the chromotropic and inotropic responses of the heart and the rates of NE overflow into the coronary sinus blood. These observations will be made in the presence and absence of cocaine. Complete heart block will be produced, so that the heart rate can be varied over a wide range by artificial pacing. The effects of diffusion on the dissipation of NE will be determined by varying the rate of coronary blood flow. The effects of bulk transport, ascribable to the massaging action of the beating heart, will be determined by varying separately the frequency and the strength of the cardiac contractions. We will also continue our investigations of the factors that govern the neuronal release of NE, especially the presynaptic effects of adenosine in the heart. We will determine the effects of exogenous and endogenous adenosine on the cardiac responses to sympathetic stimulation and on the associated rates of NE overflow into the coronary sinus blood.