McAfee D A, Henon B K, Horn J P, Yarowsky P
Fed Proc. 1981 Jun;40(8):2246-9.
The superior cervical sympathetic ganglion is currently being used as a model neuronal system for the study of Ca2+-dependent processes in the mammalian nervous system. We have characterized a regenerative calcium conductance in postganglionic neurons. This Ca2+ current contributes to the shoulder of the action potential. In addition, Ca2+ influx during the spike activates a K+ conductance, which generates a hyperpolarizing afterpotential. These Ca2+-dependent potentials are antagonized by catecholamines. Pharmacologic studies suggest that alpha 2-adrenergic receptors inhibit the regenerative voltage-dependent Ca2+ influx that occurs during the action potential. Alpha-adrenergic agonists were also found to reduce the depression of the compound action potential following a train of preganglionic stimuli. We hypothesize that alpha 2-receptors function primarily to antagonize Ca2+ influx and thereby exert significant control over neuronal excitability and release of neurotransmitters.
目前，颈上神经节正被用作研究哺乳动物神经系统中钙依赖性过程的模型神经元系统。我们已经对节后神经元中的一种再生钙电导进行了表征。这种钙离子电流对动作电位的肩部有贡献。此外，动作电位期间的钙离子内流激活了一种钾电导，产生超极化后电位。这些钙依赖性电位受到儿茶酚胺的拮抗。药理学研究表明，α2-肾上腺素能受体抑制动作电位期间发生的再生电压依赖性钙离子内流。还发现α-肾上腺素能激动剂可减少一串节前刺激后复合动作电位的衰减。我们假设α2-受体主要通过拮抗钙离子内流来发挥作用，从而对神经元兴奋性和神经递质释放进行显著控制。
