Grammatopoulos Tom N, Johnson Victoria, Moore Steve A, Andres Robert, Weyhenmeyer James A
Department of Cell and Structural Biology, University of Illinois, 346 Henry Administration Building, 506 South Wright Street, Urbana, IL 61801, USA.
Neurosci Res. 2004 Nov;50(3):299-306. doi: 10.1016/j.neures.2004.07.010.
We have previously reported that angiotensin II (Ang II) protects cortical neurons from chemical-induced hypoxia through activation of the angiotensin type 2 (AT(2)) receptor. Here, we show in mouse primary neuronal cultures that the AT(2) receptor neuroprotection results from the activation of the delayed rectifier K(+) channel as well as the involvement of the Na(+)/Ca(2+) exchanger (NCX) and Na(+)/K(+) ATPase (ATPase). Roles of the K(+) channel, NCX and ATPase were determined using the specific blockers alpha-dendrotoxin, KB-R7943 and ouabain, respectively. Sodium azide (10mM) induced apoptosis in 40% of neurons. Inhibition of the AT(1) receptor with losartan (1 microM) facilitated angiotensin II mediated neuroprotection by reducing sodium azide-induced apoptosis 61.8 +/- 5.6%, while inhibition of the AT(2) receptor with PD123319 (1 microM) showed no neuroprotection. These results suggest that angiotensin II neuroprotection is mediated through the AT(2) receptor and requires inhibition of the AT(1) receptor in order to facilitate its effect. To determine the roles of delayed rectifier K(+) channel, NCX and ATPase cultures were pretreated with alpha-dendrotoxin (10nM), KB-R7943 (100 nM) and ouabain (100 nM), which significantly attenuated AT(2) receptor mediated neuroprotection. These findings further suggest that the mechanism of AT(2) receptor mediated neuroprotection is coupled to activation of the delayed rectifier K(+) channel, NCX and ATPase.
我们之前曾报道，血管紧张素II（Ang II）通过激活血管紧张素2型（AT(2)）受体保护皮质神经元免受化学诱导的缺氧损伤。在此，我们在小鼠原代神经元培养物中表明，AT(2)受体介导的神经保护作用源于延迟整流钾（K(+)）通道的激活以及钠/钙交换体（NCX）和钠/钾ATP酶（ATPase）的参与。分别使用特异性阻滞剂α-树眼镜蛇毒素、KB-R7943和哇巴因确定了K(+)通道、NCX和ATPase的作用。叠氮化钠（10 mM）可诱导40%的神经元发生凋亡。用氯沙坦（1 μM）抑制AT(1)受体可促进血管紧张素II介导的神经保护作用，使叠氮化钠诱导的凋亡减少61.8±5.6%，而用PD123319（1 μM）抑制AT(2)受体则未显示出神经保护作用。这些结果表明，血管紧张素II的神经保护作用是通过AT(2)受体介导的，并且需要抑制AT(1)受体以促进其作用。为了确定延迟整流K(+)通道、NCX和ATPase的作用，培养物先用α-树眼镜蛇毒素（10 nM）、KB-R7943（100 nM）和哇巴因（100 nM）进行预处理，这显著减弱了AT(2)受体介导的神经保护作用。这些发现进一步表明，AT(2)受体介导的神经保护机制与延迟整流K(+)通道、NCX和ATPase的激活相关。
