Angiotensin II receptor activation depolarizes rat supraoptic neurons in vitro.
Angiotensin II receptor activation depolarizes rat supraoptic neurons in vitro.
复制标题
体外血管紧张素 II 受体激活可使大鼠视上神经元去极化。
DOI：
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发表时间：
1992
影响因子：
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通讯作者：
L. Renaud
中科院分区：
文献类型：
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作者：
C. R. Yang;M. Phillips;L. Renaud
功能研究表明，下丘脑大细胞神经分泌神经元是血管紧张素的靶点。本研究采用细胞内记录的性质和类型的血管紧张素II受体的大鼠视上核神经元维持在灌流下丘脑外植体。在短暂暴露于Val 5-或Ile 5-血管紧张素II（最大峰值浓度1-25 μ M）的68个细胞中，34个细胞的膜逐渐去极化（1-15 mV），在2.2 +/- 0.4（SD）min内达到峰值，并伴有输入电阻降低17.6 +/- 4.8%。在含有河豚毒素（0.5-1.0 μ M）和/或名义上为零钙的培养基中，反应持续存在（并且实际上增强），表明直接的突触后作用。在19个反应细胞中，血管紧张素诱导反应的平均逆转电位为-26.4 +/- 2 mV。浴应用非肽类1型血管紧张素受体拮抗剂DuP 753（5-20 μ M）可逆地阻断血管紧张素诱导的去极化在所有11个细胞测试。相比之下，2型拮抗剂PD 123177的等摩尔应用在所有7个血管紧张素反应性细胞中均无效。这些观察结果为大鼠视上核神经元上存在功能性1型受体提供了新的证据。血管紧张素诱导反应的逆转电位表明通过非选择性阳离子电导进行调解。
Functional studies indicate that hypothalamic magnocellular neurosecretory neurons are a target for angiotensin. The present investigation used intracellular recordings to characterize the nature and type of angiotensin II receptors on rat supraoptic nucleus neurons maintained in superfused hypothalamic explants. Of 68 cells transiently exposed to either Val5- or Ile5-angiotensin II (maximum peak concentration 1-25 microM), 34 responded with a gradual membrane depolarization (1-15 mV) that peaked in 2.2 +/- 0.4 (SD) min and was accompanied by a 17.6 +/- 4.8% reduction of input resistance. Responses persisted (and were actually enhanced) in media containing tetrodotoxin (0.5-1.0 microM) and/or nominally zero calcium, indicating a direct postsynaptic action. In 19 responsive cells, the mean reversal potential for the angiotensin-induced response was -26.4 +/- 2 mV. Bath application of the nonpeptide type-1 angiotensin receptor antagonist DuP753 (5-20 microM) reversibly blocked the angiotensin-induced depolarization in all of 11 cells tested. By contrast, equimolar applications of the type-2 antagonist PD123177 were ineffective in all seven angiotensin-responsive cells tested. These observations provide novel evidence for the existence of functional type-1 receptors on rat supraoptic nucleus neurons. The reversal potential for the angiotensin-induced response suggests mediation through a nonselective cationic conductance.