The origin of nitergic nerve terminals in the guinea-pig heart

用单侧颈迷走神经切断术研究了豚鼠心脏内含有一氧化氮合酶（NOS）的投射神经纤维的来源。在正常豚鼠心脏中分布有三种NOS免疫反应（NOS-ir）神经纤维：覆盖右心房的稀疏网络，位于左心房和房间隔的小神经节中围绕心内神经元胞体的篮状末梢，以及位于间隔区的轴突。左、右侧迷走神经切断后，右心房内的稀疏网状结构无明显变化。在右心房的整体标本中，我们经常追踪标记的轴突从胞体进入覆盖右心房的网络。因此，大多数这些标记的纤维网络必须是内在的起源。由于左房神经节和隔神经元胞体周围的篮状末梢在左侧迷走神经切断后完全消失，它们可能是来自左侧迷走神经的副交感节前纤维。迷走神经切断后，房室结区NOS阳性胞体和阳性纤维仍存活。所有这些神经纤维都是无髓轴突。因此，它们似乎是从位于左心房或隔的神经节发出的节后纤维。

The origin of nerve fibers projecting to the guinea pig heart that contain nitric oxide synthase (NOS) was studied by unilateral cervical vagotomy. Three kinds of NOS-immunoreactive (NOS-ir) nerve fibers are distributed in the control guinea pig heart : the sparse network covering the right atrium, the basket-like endings around intracardiac neuronal cell bodies in the small ganglia located in the left atrium and the interatrial septum, and the axons situated in the septal region. The sparse network in the right atrium did not change after vagotomy of right or left side. In the wholemount preparations of right atrium, we often traced labeled axons from the somata to join the network covering the right atrium. Therefore, most of these networks of labeled fibers must be of intrinsic origin. Because the basket-like endings around neuronal cell bodies in the ganglia in the left atrium and the septum disappeared completely after vagotomy of left side, they seem to be parasympathetic preganglionic fibers come from the left vagus nerve. NOS-ir cell bodies and the positive fibers in the atrioventricular nodal region survived after vagotomy. All of such nerve fibers were unmyelinated axons. Therefore, they seem to be the postganglionic fibers arising from the ganglia located in the left atrium or the septum.