Department of Biochemistry, University of Cambridge, Cambridge, UK.
Br J Pharmacol. 2009 Nov;158(5):1338-43. doi: 10.1111/j.1476-5381.2009.00400.x. Epub 2009 Sep 28.
It has been previously shown that high levels of nitric oxide (NO), from NO donors, kill neurones, but the mechanisms are unclear.
The effects of NO donors on the electrical properties of rat cultured cerebellar granule cells (CGC neurones) were investigated using the whole-cell patch-clamp technique.
The NO donor (Z)-1-[2-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA-NONOate or NOC-18) caused a rapid, persistent, but fully reversible inward current that was associated with an increase in baseline noise and was concentration dependent (100 microM-10 mM). The response to 3 mM DETA-NONOate was completely inhibited by 1 mM gadolinium, but not by NO scavengers (1 mM haemoglobin or 1 mM PTIO) or glutamate receptor antagonists (10 microM MK-801 or 60 microM CNQX). Application of decomposed 3 mM DETA-NONOate or 3 mM nitrite had no effect. In contrast, the NO donor S-nitrosoglutathione (GSNO) caused a rapid, persistent, but fully reversible outward current that was also concentration dependent (1-10 mM). The 3 mM GSNO response was unaltered by NO scavengers, glutamate antagonists or gadolinium, but was mimicked by decomposed 3 mM GSNO and 3 mM oxidized glutathione.
These results suggest that DETA-NONOate directly activates cation-selective channels, causing an inward current in CGCs. In contrast, GSNO causes an outward current in these cells. Some of the effects of these NO donors are independent of NO, and thus caution is required in interpreting results when using high concentrations of these compounds.
先前的研究表明，一氧化氮（NO）供体产生的高水平一氧化氮（NO）可杀死神经元，但机制尚不清楚。
采用全细胞膜片钳技术研究一氧化氮供体对大鼠培养小脑颗粒细胞（CGC 神经元）电生理特性的影响。
一氧化氮供体（Z）-1-[2-（2-氨基乙基）-N-（2-氨乙基）氨基]二氮烯-1,2-二醇盐（DETA-NONOate 或 NOC-18）引起快速、持续但完全可逆的内向电流，同时基线噪声增加，呈浓度依赖性（100 μM-10 mM）。1 mM 钆完全抑制 3 mM DETA-NONOate 的反应，但不抑制一氧化氮清除剂（1 mM 血红蛋白或 1 mM PTIO）或谷氨酸受体拮抗剂（10 μM MK-801 或 60 μM CNQX）。应用分解的 3 mM DETA-NONOate 或 3 mM 亚硝酸盐无影响。相反，NO 供体 S-亚硝基谷胱甘肽（GSNO）引起快速、持续但完全可逆的外向电流，也呈浓度依赖性（1-10 mM）。3 mM GSNO 反应不受一氧化氮清除剂、谷氨酸拮抗剂或钆的影响，但可被分解的 3 mM GSNO 和 3 mM 氧化型谷胱甘肽模拟。
这些结果表明，DETA-NONOate 直接激活阳离子选择性通道，在 CGC 中引起内向电流。相比之下，GSNO 在这些细胞中引起外向电流。这些 NO 供体的一些作用与 NO 无关，因此在使用这些化合物的高浓度时，需要谨慎解释结果。
