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进行细胞内记录，研究吻侧腹外侧髓质（RVLM）推定的前交感神经元的电生理特性，并确定RVLM神经元电生理特性的变化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，其中交感神经网络被认为被保留，不像切片制备。我们将RVLM前交感神经元分为3种类型。(I)有规律放电神经元（n=20），表现出斜坡去极化和频繁的动作电位（APs, 3.6 * 1.1 spike /sec），而兴奋性突触后电位（EPSPs）较少；(2)“不规则放电神经元”（n=106），表现出许多调节放电速率的EPSPs和抑制性psp；(3)“沉默型神经元”（n=25），仅在电流诱导的去极化过程中释放ap。在阻断突触输入的低ca ^<2+>-高mg ^<2+>灌注时，更多的放电神经元保持正常放电，而12个不规则放电神经元中有8个放电被取消。这些结果表明，有规律的放电神经元独立于突触输入而放电。在Th2水平上刺激中外侧细胞柱（IML）后，151个RVLM神经元中有33个出现了持续潜伏期的反向ap。31个RVLM神经元中有19个在迷走神经传入刺激下被抑制或增强。综上所述，我们利用全细胞膜片钳技术在脑干-脊髓制备中对三种类型的RVLM前交感神经元进行了表征，证实了迷走神经传入神经经RVLM到达IML的通路被保留。由于在所有三种类型的一些神经元中都证明了反行性ap和对迷走传入刺激的反应，因此所有类型的RVLM神经元都可能构成交感神经网络的关键部分。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