Angiotensin II excites paraventricular nucleus neurons that innervate the rostral ventrolateral medulla: An in vitro patch-clamp study in brain slices
Angiotensin II excites paraventricular nucleus neurons that innervate the rostral ventrolateral medulla: An in vitro patch-clamp study in brain slices
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DOI：
10.1152/jn.01055.2003
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发表时间：
2005-01-01
影响因子：
2.5
通讯作者：
Toney, GM
中科院分区：
文献类型：
--
作者：
Cato, MJ;Toney, GM
下丘脑室旁核（PVN）的神经元是交感神经活动的关键控制器，并接受前脑中含血管紧张素II（ANG II）神经元的输入。本研究确定了血管紧张素II对延髓头端腹外侧区（RVLM）神经支配的PVN神经元的影响，RVLM是维持交感神经流出和动脉压的关键脑干部位。采用离体脑片制备方法，对大鼠同侧RVLM逆行标记的PVN神经元进行全细胞膜片钳记录。71个神经元测试，62（87%）响应ANG II。在电流钳模式下，浴用ANG Ⅱ（2 μ M）显著（P < 0.05）使膜电位从-58.5 +/-2.5到-54.5 +/-2.0 mV去极化，并使动作电位放电频率从0.7 +/-0.3增加到2.8 +/-0.8 Hz（n = 4）。局部应用血管紧张素II的低压喷射从玻璃移液管（2 pmol，0.4 nl，5 s）也引起了快速和可重复的兴奋，在17个20个细胞。在该组中，膜电位去极化平均值为21.5 +/- 4.1 mV，峰电位活动从0.7 +/- 0.4增加到21.3 +/- 3.3 Hz。在电压钳模式下，47个神经元中的41个对压力喷射的ANG II产生剂量依赖性内向电流，在最大有效剂量为2.0 pmol时平均为-54.7 +/-3.9 pA。阻断ANG Ⅱ AT 1受体可显著减少局部应用ANG Ⅱ引起的放电（P < 0.001，n = 5）、去极化（P < 0.05，n = 3）和内向电流（P < 0.01，n = 11）。在6个测试的细胞中，在局部应用ANG II（2 pmol）期间，膜输入电导增加（P < 0.001），表明阳离子内流。ANG II电流在+2.2 +/-2.2mV（n = 9）时极性反转，并被钆（Gd 3+，100 μ M，n = 8）浴灌注阻断（P < 0.01），表明ANG II激活对阳离子非选择性渗透的膜通道。这些研究结果表明，ANG II兴奋PVN神经元，神经支配同侧RVLM的机制，依赖于AT 1受体的激活和门控的一个或多个类别的离子通道，导致混合阳离子电流。
Neurons of the hypothalamic paraventricular nucleus (PVN) are key controllers of sympathetic nerve activity and receive input from angiotensin II (ANG II) - containing neurons in the forebrain. This study determined the effect of ANG II on PVN neurons that innervate in the rostral ventrolateral medulla (RVLM) - a brain stem site critical for maintaining sympathetic outflow and arterial pressure. Using an in vitro brain slice preparation, whole cell patchclamp recordings were made from PVN neurons retrogradely labeled from the ipsilateral RVLM of rats. Of 71 neurons tested, 62 (87%) responded to ANG II. In current-clamp mode, bath-applied ANG II ( 2 muM) significantly ( P < 0.05) depolarized membrane potential from - 58.5 +/- 2.5 to - 54.5 +/- 2.0 mV and increased the frequency of action potential discharge from 0.7 +/- 0.3 to 2.8 +/- 0.8 Hz ( n = 4). Local application of ANG II by low-pressure ejection from a glass pipette ( 2 pmol, 0.4 nl, 5 s) also elicited rapid and reproducible excitation in 17 of 20 cells. In this group, membrane potential depolarization averaged 21.5 +/- 4.1 mV, and spike activity increased from 0.7 +/- 0.4 to 21.3 +/- 3.3 Hz. In voltage- clamp mode, 41 of 47 neurons responded to pressure-ejected ANG II with a dose-dependent inward current that averaged - 54.7 +/- 3.9 pA at a maximally effective dose of 2.0 pmol. Blockade of ANG II AT1 receptors significantly reduced discharge ( P < 0.001, n = 5), depolarization ( P < 0.05, n = 3), and inward current ( P < 0.01, n = 11) responses to locally applied ANG II. In six of six cells tested, membrane input conductance increased ( P < 0.001) during local application of ANG II ( 2 pmol), suggesting influx of cations. The ANG II current reversed polarity at + 2.2 +/- 2.2 mV ( n = 9) and was blocked ( P < 0.01) by bath perfusion with gadolinium (Gd3+, 100 muM, n = 8), suggesting that ANG II activates membrane channels that are nonselectively permeable to cations. These findings indicate that ANG II excites PVN neurons that innervate the ipsilateral RVLM by a mechanism that depends on activation of AT1 receptors and gating of one or more classes of ion channels that result in a mixed cation current.