Aims

Nitric oxide synthases (NOSs) are key enzymes regulating vascular function. Previously, we reported that β-adrenergic (β-AR) overstimulation, a common feature of cardiovascular diseases, did not impair endothelium-dependent vasodilation, although it resulted in endothelial NOS (eNOS) uncoupling and reduced NO bioavailability. In addition to NO, neuronal NOS (nNOS) produces H₂O₂, which contributes to vasodilation. However, there is limited information regarding vascular β-AR signaling and nNOS. In the present study, we assessed the possible role of nNOS-derived H₂O₂ and caveolins on endothelial vasodilation function following β-AR overstimulation.

Main methods

Male C57BL/6 wild-type and nNOS knockout mice (nNOS^−/−) were treated with the β-AR agonist isoproterenol (ISO, 15 mg·kg⁻¹·day⁻¹, s.c.) or vehicle (VHE) for seven days. Relaxation responses of aortic rings were evaluated using wire myograph and H₂O₂ by Amplex Red.

Key findings

Acetylcholine- or calcium ionophore A23187-induced endothelium-dependent relaxation was similar in aortic rings from VHE and ISO. However, this relaxation was significantly reduced in aortas from ISO compared to VHE when (1) caveolae were disrupted, (2) nNOS was pharmacologically inhibited or genetically suppressed and (3) H₂O₂ was scavenged. NOS-derived H₂O₂ production was higher in the aortas of ISO mice than in those of VHE mice. Aortas from ISO-treated mice showed increased expression of caveolin-1, nNOS and catalase, while caveolin-3 expression did not change.

Significance

The results suggest a role of caveolin-1 and the nNOS/H₂O₂ vasodilatory pathway in endothelium-dependent relaxation following β-AR overstimulation and reinforce the protective role of nNOS in cardiovascular diseases associated with high adrenergic tone.

中文翻译：

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神经元一氧化氮合酶在慢性β-肾上腺素能受体过度刺激中内皮血管舒张中的保护作用

宗旨

一氧化氮合酶 (NOS) 是调节血管功能的关键酶。之前，我们报道了 β-肾上腺素能 (β-AR) 过度刺激是心血管疾病的一个共同特征，它不会损害内皮依赖性血管舒张，尽管它会导致内皮 NOS (eNOS) 解偶联并降低 NO 生物利用度。除了 NO，神经元 NOS (nNOS) 还会产生 H ₂ O ₂，这有助于血管舒张。然而，关于血管 β-AR 信号传导和 nNOS 的信息有限。在本研究中，我们评估了 nNOS 衍生的 H ₂ O ₂和小窝蛋白对 β-AR 过度刺激后内皮血管舒张功能的可能作用。

主要方法

雄性 C57BL/6 野生型和 nNOS 敲除小鼠 (nNOS ^-/- ) 用 β-AR 激动剂异丙肾上腺素 (ISO, 15 mg·kg ^-1 ·day ^-1 , sc ) 或载体 (VHE) 治疗 7 天. 使用线肌描记器和Amplex Red 的H ₂ O ₂评估主动脉环的松弛反应。

主要发现

乙酰胆碱或钙离子载体 A23187 诱导的内皮依赖性松弛在来自 VHE 和 ISO 的主动脉环中相似。然而，与 VHE 相比，当 (1) 细胞膜穴样内陷被破坏，(2) nNOS 被药理抑制或基因抑制以及 (3) H ₂ O ₂被清除时，ISO 主动脉中的这种松弛显着减少。与 VHE 小鼠相比，ISO 小鼠主动脉中NOS 衍生的 H ₂ O ₂产量更高。ISO处理小鼠的主动脉显示caveolin-1、nNOS和过氧化氢酶的表达增加，而caveolin-3的表达没有变化。

意义

结果表明，caveolin-1 和 nNOS/H ₂ O ₂血管舒张途径在 β-AR 过度刺激后的内皮依赖性舒张中起作用，并加强了 nNOS 在与高肾上腺素能张力相关的心血管疾病中的保护作用。