Rimmer Katrina, Harper Alexander A
Division of Molecular Physiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom.
J Neurophysiol. 2006 Jun;95(6):3543-52. doi: 10.1152/jn.01220.2005. Epub 2006 Apr 12.
We charted postnatal changes in the intrinsic electrophysiological properties and synaptic responses of rat intrinsic cardiac ganglion (ICG) neurons. We developed a whole-mount ganglion preparation of the excised right atrial ganglion plexus. Using intracellular recordings and nerve stimulation we tested the hypothesis that substantial transformations in the intrinsic electrical characteristics and synaptic transmission accompany postnatal development. Membrane potential (E(m)) did not change but time constant (tau) and cell capacitance increased with postnatal development. Accordingly, input resistance (R(in)) decreased but specific membrane resistance (R(m)) increased postnatally. Comparison of the somatic active membrane properties revealed significant changes in electrical phenotype. All neonatal neurons had somatic action potentials (APs) with small overshoots and small afterhyperpolarizations (AHPs). Adult neurons had somatic APs with large overshoots and large AHP amplitudes. The range of AHP duration was larger in adults than in neonates. The AP characteristics of juvenile neurons resembled those of adults, with the exception of AHP duration, which fell midway between neonate and adult values. Phasic, multiply adapting, and tonic evoked discharge activities were recorded from ICG neurons. Most neurons displayed phasic discharge at each developmental stage. All neurons received excitatory synaptic inputs from the vagus or interganglionic nerve trunk(s), the strength of which did not change significantly with postnatal age. The changes in the electrophysiological properties of the postganglionic neuron suggest that increased complexity of parasympathetic regulation of cardiac function accompanies postnatal development.
我们绘制了大鼠心脏固有神经节（ICG）神经元固有电生理特性和突触反应的产后变化。我们开发了一种切除右心房神经节丛的整装神经节标本。使用细胞内记录和神经刺激，我们检验了以下假设：产后发育伴随着固有电特性和突触传递的实质性转变。膜电位（E(m)）没有变化，但时间常数（tau）和细胞电容随产后发育而增加。相应地，输入电阻（R(in)）降低，但比膜电阻（R(m)）在出生后增加。对体细胞主动膜特性的比较揭示了电表型的显著变化。所有新生神经元的体细胞动作电位（APs）超射小，后超极化（AHPs）小。成年神经元的体细胞APs超射大，AHP幅度大。成年动物AHP持续时间的范围比新生动物大。幼年神经元的AP特征与成年神经元相似，除了AHP持续时间，其介于新生和成年值之间。从ICG神经元记录到了相位性、多重适应性和紧张性诱发放电活动。大多数神经元在每个发育阶段都表现出相位性放电。所有神经元都接受来自迷走神经或神经节间神经干的兴奋性突触输入，其强度不会随产后年龄而显著变化。节后神经元电生理特性的变化表明，随着产后发育，心脏功能的副交感神经调节复杂性增加。
