INVITRO CHARACTERIZATION OF NEURONS IN THE VENTRAL PART OF THE NUCLEUS TRACTUS SOLITARIUS .2. IONIC BASIS FOR REPETITIVE FIRING PATTERNS
INVITRO CHARACTERIZATION OF NEURONS IN THE VENTRAL PART OF THE NUCLEUS TRACTUS SOLITARIUS .2. IONIC BASIS FOR REPETITIVE FIRING PATTERNS
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DOI：
10.1152/jn.1987.58.1.215
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发表时间：
1987-07-01
影响因子：
2.5
通讯作者：
GETTING, PA
中科院分区：
文献类型：
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作者：
DEKIN, MS;GETTING, PA
1.豚鼠孤束核腹侧部由背侧呼吸群组成，由三类神经元组成。它们被称为类型I、II和III。每种类型的细胞都有一组独特的重复激发特性。体外脑干切片制备被用来研究这些重复激发特性的离子基础。2.三种不同的膜电流对重复放电特性有一定的影响。它们是：慢钙电流(ICa)、早期瞬时钾电流(Ika)和钙激活钾电流(Ikc)。I型和II型神经元显示出生理上显著数量的这些电流，而III型神经元则没有。3.在从-50 mV到-60 mV的电位水平去极化时，I型和II型神经元的重复放电特性主要由ICA和IkC决定。在这个潜在的范围内，Ika被灭活了。I型神经元中IKC的表达高于II型神经元，因此，I型神经元在去极化早期表现出一种自我终止的峰活动爆发，而II型神经元在整个去极化过程中表现出峰频率的逐渐下降。4.用单电极电压钳技术研究了I型和II型神经元IkA的特性。I型神经元的IKA动力学速度大约是II型神经元的两倍。此外，I型神经元IKA的激活和去失活的电压依赖性相对于II型神经元移动了约-10 mV。5.I型神经元从膜电位水平去极化，去除IkA的失活，导致初始峰电位爆发的频率降低。这种尖峰频率的下降是IKA和ICA共同激活的结果。6.去除IkA失活的膜电位对II型神经元的去极化作用，使去极化开始和放电开始之间有较长时间的延迟。兴奋延迟受刺激前超极化的幅度和持续时间的调节。这种延迟兴奋的调制与消除II型神经元中IKA失活的时间和电压依赖是平行的。
1. The ventrl part of the nucleus tractus solitarius in guinea pigs comprises the dorsal respiratory group and is composed of three classes of neurons. These have been termed types I, II, and III. Each cell type possesses a unique set of repetitive firing properties. An in vitro brain stem slice preparation was used to study the ionic basis for these repetitive firing properties. 2. Three different membrane currents were shown to contribute to the repetitive firing properties. These were: a slow calcium current (ICa), an early, transient potassium current (IKA), and a calcium-activated potassium current (IKC). Type I and II neurons displayed physiologically significant amounts of these currents; type III neurons did not. 3. During depolarization from potential levels beteeen -50 and -60 mV, the repetitive firing properties of type I and II neurons were determined primarily by ICa and IKC. IKA was inactivated in this potential range. The expression of IKC was greater in type I neurons than in type II neurons, and as a result, type I neurons exhibited a self-terminating burst of spike activity early in depolarization, whereas type II neurons displayed a gradual decline in spike frequency throughout depolarization. 4. The properites of IKA in type I and II neurons were studied using the single-electrode voltage-clamp technique. The kinetics of IKA in type I neurons was approximately twice as slow as those of type II neurons. In addition, the voltage dependence of activation and the removal of inactivation for IKA in type I neurons were shifted by about -10 mV with respect to type II neurons. 5. Depolarization of type I neurons from membrane potential level where inactivation of IKA was removed caused a decrease in the frequency of the initial burst of spikes. This decrease in spiked frequency was a result of the coactivation of IKA with ICa. 6. Depolarization of type II neurons from membrane potentials where inactivation of IKA was removed caused a long delay between the onset of depolarization and the beginning of spike activity. The delay in excitation was modulated by both the magnitude and duration of the prestimulus hyperpolarization. This modulation of delayed excitation paralleled the time and voltage dependence for the removal of IKA inactivation in type II neurons.