Zafari A M, Ushio-Fukai M, Akers M, Yin Q, Shah A, Harrison D G, Taylor W R, Griendling K K
From the Department of Medicine, Division of Cardiology, Emory University, Atlanta, GA 30322, USA.
Hypertension. 1998 Sep;32(3):488-95. doi: 10.1161/01.hyp.32.3.488.
Recent evidence suggests that oxidative mechanisms may be involved in vascular smooth muscle cell (VSMC) hypertrophy. We previously showed that angiotensin II (Ang II) increases superoxide production by activating an NADH/NADPH oxidase, which contributes to hypertrophy. In this study, we determined whether Ang II stimulation of this oxidase results in H2O2 production by studying the effects of Ang II on intracellular H2O2 generation, intracellular superoxide dismutase and catalase activity, and hypertrophy. Ang II (100 nmol/L) significantly increased intracellular H2O2 levels at 4 hours. Neither superoxide dismutase activity nor catalase activity was affected by Ang II; the SOD present in VSMCs is sufficient to metabolize Ang II-stimulated superoxide to H2O2, which accumulates more rapidly than it is degraded by catalase. This increase in H2O2 was inhibited by extracellular catalase, diphenylene iodonium, an inhibitor of the NADH/NADPH oxidase, and the AT1 receptor blocker losartan. In VSMCs stably transfected with antisense p22phox, a critical component of the NADH/NADPH oxidase in which oxidase activity was markedly reduced, Ang II-induced production of H2O2 was almost completely inhibited, confirming that the source of Ang II-induced H2O2 was the NADH/NADPH oxidase. Using a novel cell line that stably overexpresses catalase, we showed that this increased H2O2 is a critical step in VSMC hypertrophy, a hallmark of many vascular diseases. Inhibition of intracellular superoxide dismutase by diethylthiocarbamate (1 mmol/L) also resulted in attenuation of Ang II-induced hypertrophy (62+/-2% inhibition). These data indicate that AT1 receptor-mediated production of superoxide generated by the NADH/NADPH oxidase is followed by an increase in intracellular H2O2, suggesting a specific role for these oxygen species and scavenging systems in modifying the intracellular redox state in vascular growth.
最近的证据表明，氧化机制可能参与血管平滑肌细胞（VSMC）肥大。我们之前发现，血管紧张素II（Ang II）通过激活NADH/NADPH氧化酶增加超氧化物生成，这促进了肥大。在本研究中，我们通过研究Ang II对细胞内H2O2生成、细胞内超氧化物歧化酶和过氧化氢酶活性以及肥大的影响，来确定Ang II对该氧化酶的刺激是否会导致H2O2生成。Ang II（100 nmol/L）在4小时时显著增加细胞内H2O2水平。超氧化物歧化酶活性和过氧化氢酶活性均不受Ang II影响；VSMC中存在的超氧化物歧化酶足以将Ang II刺激产生的超氧化物代谢为H2O2，其积累速度比被过氧化氢酶降解的速度更快。细胞外过氧化氢酶、NADH/NADPH氧化酶抑制剂二苯碘鎓以及AT1受体阻滞剂氯沙坦可抑制这种H2O2的增加。在稳定转染反义p22phox（NADH/NADPH氧化酶的关键成分，其氧化酶活性显著降低）的VSMC中，Ang II诱导的H2O2生成几乎被完全抑制，证实Ang II诱导的H2O2来源是NADH/NADPH氧化酶。使用一种稳定过表达过氧化氢酶的新型细胞系，我们发现这种增加的H2O2是VSMC肥大的关键步骤，而VSMC肥大是许多血管疾病的一个标志。二乙硫代氨基甲酸盐（1 mmol/L）抑制细胞内超氧化物歧化酶也导致Ang II诱导的肥大减弱（抑制率为62±2%）。这些数据表明，AT1受体介导的由NADH/NADPH氧化酶产生的超氧化物之后细胞内H2O2增加，提示这些氧物种和清除系统在改变血管生长中的细胞内氧化还原状态方面具有特定作用。
