NEURAL CONTROL OF THE HEART

这个项目的长期目标是获得更彻底的 了解自主神经对心脏功能的控制。这个 心脏迷走神经传出纤维的活动特征 由每个心脏周期的动作电位爆发组成。具体的 拟议实验的目的是(1)确定心脏的影响。 这种传出迷走神经爆发的时间模式的变化 活动，(2)确定节前轴突的会聚程度 来自左右迷走神经的节后副交感神经 心内神经节中的神经元，以及(3)测定 反复爆发迷走神经活动对个体成分的影响 可能是多中心右心房起搏器复合体。大多数 研究将在开胸麻醉的狗身上进行。一台计算机 将控制每个刺激脉冲串中的脉冲数量，间隔时间 每个脉冲串中的单个脉冲以及每个脉冲串中的每个脉冲串的时间 心跳周期。神经传递的“便利化”程度将是 通过将对刺激突发事件的总体反应与 不同数量的脉冲。类似的研究也将在 孤立的，迷走神经支配的鸡心。在迷走神经刺激过程中， 容易检测到的乙酰胆碱(ACh)从 孤立的鸡心。这样的实验将使我们能够将 心脏的力学行为，以ACh的溢出为基础 迷走神经刺激爆发的特征被改变。在研究中 关于多中心起搏器复合体的同步，180个阵列 电极在右心房外表面的应用 麻醉犬将允许产生激活序列和 潜在的分布图。从这样的地图上可以看出 迷走神经刺激爆发在起始点和起始点的特点 可以确定心脏兴奋的协调性。

The long-term objective of this project is to gain a more thorough understanding of the autonomic neural control of cardiac function. The characteristic pattern of activity in efferent cardiac vagal fibers consists of a burst of action potentials each cardiac cycle. The specific aims of the proposed experiments are (1) to determine the cardiac effects of changes in the temporal pattern of such bursts of efferent vagal activity, (2) to determine the extent of convergence of preganglionic axons from the right and left vagus nerves on the postganglionic parasympathetic neurons in the intracardiac ganglia, and (3) to determine the synchronizing effects of repetitive bursts of vagal activity on the individual components of a putative multicentric right atrial pacemaker complex. Most of the studies will be carried out in open-chest, anesthetized dogs. A computer will control the number of pulses in each stimulus burst, the time between individual pulses in each burst, and the time of each burst within each cardiac cycle. The extent of "facilitation" of neurotransmission will be assessed by comparing the overall responses to stimulus bursts with different numbers of pulses. Similar studies will also be carried out in isolated, vagally innervated chicken hearts. During vagal stimulation, easily detectable quantities of acetylcholine (ACh) overflow from the isolated chicken heart. Such experiments will enable us to correlate the mechanical behavior of the heart with the overflow of ACh as the characteristics of the vagal stimulus bursts are altered. In the studies on synchronization of the multicentric pacemaker complex, an array of 180 electrodes applied to the external surface of the right atrium of anesthetized dogs will permit the generation of activation sequence and potential distribution maps. From such maps the effects of changes in the characteristics of the vagal stimulus bursts on the initiation and coordination of cardiac excitation can be determined.