Calcium channels of rostral ventrolateral medulla neurons of hypertensive rats studies by patch-clamp technique

采用全细胞膜片钳技术对延髓头端腹外侧区（RVLM）的前交感神经元进行细胞内记录，以探讨RVLM神经元电生理特性的改变是否与高血压的发生有关。我们利用新生大鼠脑干-脊髓制备，其中交感神经元网络被认为是保留的，而不像在切片中。我们将RVLM前交感神经元分为3种类型。(I)'规则放电神经元（n=20），表现为斜坡去极化和频繁动作电位（2）“不规则放电神经元”（n=106），表现出许多兴奋性突触后电位（EPSP）和抑制性突触后电位（PSP），它们调节放电频率;（3）“沉默型神经元”（n=25），只在电流诱导的去极化过程中放电AP.所有的定期 关于我们 在阻断突触输入的低Ca ^2+-高Mg ^2+灌流过程中，放电神经元保留了它们的规则放电，而12个不规则放电神经元中有8个的放电被消除。这些结果表明，规则放电神经元的放电不依赖于突触输入.在Th 2水平刺激中间外侧细胞柱（intermediolateral cell column，IML）后，151个RVLM神经元中有33个出现了具有恒定潜伏期的逆向AP。在31个RVLM前交感神经元中，有19个被迷走神经传入刺激抑制或增强。总之，在脑干-脊髓标本中，我们用全细胞膜片钳技术对RVLM前交感神经元进行了表征，证实了迷走神经传入通过RVLM到达IML的通路得以保留。由于逆向AP和迷走神经传入刺激的反应在所有3种类型的一些神经元中被证明，所有类型的RVLM神经元潜在地构成交感神经元网络的关键部分。少

Intracellular recordings were performed by the whole-cell patch-clamp technique to study the electrophysiological properties of putative presympathetic neurons in the rostral ventrolateral medulla (RVLM) and to determine whether the changes in electrophysiological characteristics of RVLM neurons contribute to genesis of hypertension. We utilized the neonatal rat brainstem-spinal cord preparation, in which the sympathetic neuronal network is thought to be preserved, unlike in slice preparation.1. We classified and characterized RVLM presympathetic neurons into 3 types. (I) 'regularly firing neurons (n=20), which showed ramp depolarization and frequent action potentials (APs, 3.6 * 1.1 spikes/sec) with rare excitatory postsynaptic potentials (EPSPs) ; (2) 'irregularly firing neurons' (n=106), which exhibited many EPSPs and inhibitory PSPs that modulated the firing rate ; (3) 'silent-type neurons' (n=25), which discharged APs only during current-induced depolarization.2. All of regularly … More firing neurons retained their regular discharges during low-Ca^<2+>-high-Mg^<2+> superfusion that blocks synaptic inputs, whereas the discharge in 8 of 12 irregularly firing neurons was abolished. These results suggest that the regularly firing neurons discharge independently of synaptic inputs.3. After stimulation of intermediolateral cell column (IML) at the Th2 level, 33 of 151 RVLM neurons showed antidromic APs with a constant latency. Nineteen of 31 RVLM neurons were inhibited or potentiated by vagal afferent stimulation.In summary, three types of RVLM presympathetic neurons were characterized by the whole-cell patch-clamp technique in the brainstem-spinal cord preparation, in which we confirmed that pathway from vagal afferents to the IML through the RVLM was preserved. Since antidromic APs and the responses to vagal afferent stimulation were demonstrated in some neurons of all 3 types, all types of RVLM neurons potentially constitute a critical part of the sympathetic neuronal network. Less