Hayakawa H, Hirata Y, Kakoki M, Suzuki Y, Nishimatsu H, Nagata D, Suzuki E, Kikuchi K, Nagano T, Kangawa K, Matsuo H, Sugimoto T, Omata M
The Third Department of Internal Medicine, Kanto Central Hospital, Tokyo, Japan.
Hypertension. 1999 Feb;33(2):689-93. doi: 10.1161/01.hyp.33.2.689.
We previously reported that adrenomedullin (AM), a potent vasodilator peptide discovered in pheochromocytoma cells, stimulates nitric oxide (NO) release in the rat kidney. To further investigate whether the NO-cGMP pathway is involved in the mechanisms of AM-induced vasodilation, we examined the effects of E-4021, a cGMP-specific phosphodiesterase inhibitor, on AM-induced vasorelaxation in aortic rings and perfused kidneys isolated from Wistar rats. We also measured NO release from the kidneys using a chemiluminescence assay. AM (10(-10) to 10(-7) mol/L) relaxed the aorta precontracted with phenylephrine in a dose-dependent manner. Denudation of endothelium (E) attenuated the vasodilatory action of AM (10(-7) mol/L AM: intact (E+) -25.7+/-5.2% versus denuded (E-) -7. 8+/-0.6%, P<0.05). On the other hand, pretreatment with 10(-8) mol/L E-4021 augmented AM-induced vasorelaxation in the intact aorta (-49. 0+/-7.9%, P<0.05) but not in the denuded one. E-4021 also enhanced acetylcholine (ACh)-induced vasorelaxation in the rat intact aorta (10(-7) mol/L ACh -36.6+/-8.4% versus 10(-8) mol/L E-4021+10(-7) mol/L ACh -62.7+/-3.1%, P<0.05). In perfused kidneys, AM-induced vasorelaxation was also augmented by preincubation with E-4021 (10(-9) mol/L AM -15.4+/-0.6% versus 10(-8) mol/L E-4021+10(-9) mol/L AM -23.6+/-1.2%, P<0.01). AM significantly increased NO release from rat kidneys (DeltaNO: +11.3+/-0.8 fmol. min-1. g-1 kidney at 10(-9) mol/L AM), which was not affected by E-4021. E-4021 enhanced ACh-induced vasorelaxation (10(-9) mol/L ACh -9.7+/-1.7% versus 10(-8) mol/L E-4021+10(-9) mol/L ACh -18.8+/-2.9%, P<0.01) but did not affect ACh-induced NO release from the kidneys. In the aorta and the kidney, 10(-4) mol/L of NG-nitro-L-arginine methyl ester, an NO synthase inhibitor, and 10(-5) mol/L of methylene blue, a guanylate cyclase inhibitor, reduced the vasodilatory effect of AM. These results suggest that the NO-cGMP pathway is involved in the mechanism of AM-induced vasorelaxation, at least in the rat aorta and kidney.
我们之前报道过，肾上腺髓质素（AM）是一种在嗜铬细胞瘤细胞中发现的强效血管舒张肽，可刺激大鼠肾脏释放一氧化氮（NO）。为了进一步研究NO - cGMP途径是否参与AM诱导的血管舒张机制，我们检测了cGMP特异性磷酸二酯酶抑制剂E - 4021对从Wistar大鼠分离的主动脉环和灌注肾脏中AM诱导的血管舒张的影响。我们还使用化学发光分析法测量了肾脏释放的NO。AM（10⁻¹⁰至10⁻⁷mol/L）以剂量依赖性方式使预先用去氧肾上腺素收缩的主动脉舒张。内皮剥脱（E）减弱了AM的血管舒张作用（10⁻⁷mol/L AM：完整（E⁺）-25.7±5.2% 对比 剥脱（E⁻）-7.8±0.6%，P<0.05）。另一方面，用10⁻⁸mol/L E - 4021预处理可增强完整主动脉中AM诱导的血管舒张（-49.0±7.9%，P<0.05），但在剥脱的主动脉中则不然。E - 4021还增强了大鼠完整主动脉中乙酰胆碱（ACh）诱导的血管舒张（10⁻⁷mol/L ACh -36.6±8.4% 对比 10⁻⁸mol/L E - 4021 + 10⁻⁷mol/L ACh -62.7±3.1%，P<0.05）。在灌注肾脏中，用E - 4021预孵育也增强了AM诱导的血管舒张（10⁻⁹mol/L AM -15.4±0.6% 对比 10⁻⁸mol/L E - 4021 + 10⁻⁹mol/L AM -23.6±1.2%，P<0.01）。AM显著增加大鼠肾脏释放的NO（在10⁻⁹mol/L AM时，ΔNO：+11.3±0.8 fmol·min⁻¹·g⁻¹肾脏），这不受E - 4021影响。E - 4021增强了ACh诱导的血管舒张（10⁻⁹mol/L ACh -9.7±1.7% 对比 10⁻⁸mol/L E - 4021 + 10⁻⁹mol/L ACh -18.8±2.9%，P<0.01），但不影响ACh诱导的肾脏NO释放。在主动脉和肾脏中，10⁻⁴mol/L的NO合酶抑制剂NG - 硝基 - L - 精氨酸甲酯和10⁻⁵mol/L的鸟苷酸环化酶抑制剂亚甲蓝降低了AM的血管舒张作用。这些结果表明，NO - cGMP途径至少在大鼠主动脉和肾脏中参与了AM诱导的血管舒张机制。
