Zheng X F, Kwan C Y, Daniel E E
Department of Physiology, University of Hong Kong.
Zhongguo Yao Li Xue Bao. 1995 Sep;16(5):385-90.
To examine the possible role of agents elevating cAMP to release NO from aortic endothelial cells.
NG-nitro-L-arg inine methylester (L-NAME), an inhibitor of NO synthase, partially inhibited endothelium-dependent relaxation evoked in phenylephrine-precontracted rings by isoproterenol and abolished relaxation mediated by forskolin 0.2 mumol L-1.
In rings without endothelium, isoproterenol and forskolin were less effective relaxants and L-NAME had no effect on the responses. In methylene blue-treated rings isoproterenol- and forskolin-induced relaxation were prevented in both endothelium-intact and -denuded rings, but the inhibitory effect of methylene blue were significantly more in rings with endothelium than in those without. On the other hand, relaxation induced by sodium nitroprusside was not inhibited by L-NAME, but was inhibited by methylene blue in both the endothelium-intact and -denuded rings. The concentration-relaxation curves to sodium nitroprusside after methylene blue were identical for rings with and without endothelium.
beta-Adrenoceptors or any agent which raises cAMP elevate NO release from endothelial cells.
研究提高环磷酸腺苷（cAMP）水平的药物从主动脉内皮细胞释放一氧化氮（NO）的可能作用。
NO合酶抑制剂N-硝基-L-精氨酸甲酯（L-NAME）部分抑制了异丙肾上腺素在苯肾上腺素预收缩环中诱发的内皮依赖性舒张，并消除了0.2μmol/L福司可林介导的舒张作用。
在无内皮的环中，异丙肾上腺素和福司可林的舒张作用较弱，L-NAME对反应无影响。在亚甲蓝处理的环中，异丙肾上腺素和福司可林诱导的舒张在有内皮和无内皮的环中均被阻止，但亚甲蓝的抑制作用在有内皮的环中比在无内皮的环中明显更强。另一方面，硝普钠诱导的舒张不受L-NAME抑制，但在有内皮和无内皮的环中均受亚甲蓝抑制。亚甲蓝处理后硝普钠的浓度-舒张曲线在有内皮和无内皮的环中相同。
β-肾上腺素能受体或任何提高cAMP水平的药物均可增加内皮细胞释放NO。
