The ability of various nitric oxide (NO) donors to induce long-lasting inhibition of contraction in isolated arteries was compared. All the studied compounds elicited a relaxant effect in rat aortic rings precontracted with norepinephrine (NE). Almost maximal relaxation was obtained with 1 μM of each compound. The S -nitrosating agents S- nitrosoglutathione (GSNO), S -nitroso- N -acetylpenicillamine, S -nitroso- N -acetylcysteine, and sodium nitroprusside (1 μM) produced a decrease of the maximal effect of NE that persisted after removal of the drug. This hyporesponsiveness to NE was associated with a relaxant effect of N- acetylcysteine, a low-molecular weight thiol that can displace NO from cysteine-NO bonds. Such modifications of contraction were not observed in aortic rings previously exposed to 1 μM S- nitrosocysteine, glyceryl trinitrate, 3-morpholinosydnonimine, or 2-( N , N -diethylamino)-diazenolate-2-oxide (DEA-NO). The same differential effects of GSNO and DEA-NO on contraction were also observed in porcine coronary arteries. Rat aortic rings previously exposed to 100 μM GSNO, but not to 100 μM DEA-NO, displayed a persistent increase in NO content (determined by NO spin trapping) and cysteine-NO residues (determined by immunostaining with an anti-cysteine-NO antiserum). The GSNO-induced increase in cysteine-NO residues in aortic tissue was prevented by the thiolmodifying agent p -hydroxymercuribenzoic acid. This study shows that in isolated arteries, the effects of S- nitrosating agents differed from those of other NO-donating agents. S- Nitrosating agents induced a persistent inhibition of contraction, which was attributed to the formation of releasable NO stores by S- nitrosation of tissue thiols. These differential effects of NO donors may be important for orientating their therapeutic indications.
研究人员比较了各种
一氧化氮(NO)供体诱导离体动脉持久抑制收缩的能力。所有研究化合物都能在
去甲肾上腺素(NE)预收缩的大鼠主动脉环中产生松弛作用。每种化合物在 1 μM 的浓度下几乎都能获得最大的松弛作用。S-亚硝基化剂 S-亚硝基
谷胱甘肽(GSNO)、S-亚硝基-
N-乙酰青霉胺、
S-亚硝基-N-乙酰半胱氨酸和
硝普钠(1 μM)会降低 NE 的最大效应,这种效应在去除药物后仍然存在。这种对 NE 的低反应性与 N-乙酰半胱
氨酸的松弛作用有关,N-乙酰半胱
氨酸是一种低分子量的
硫醇,可将 NO 从半胱
氨酸-NO 键置换出来。在之前暴露于 1 μM
S-亚硝基半胱氨酸、三
硝酸甘油酯、3-吗啉基二壬
亚胺或 2-( N , N -
二乙基氨基)-二
苯酚-2-氧化物(
DEA-NO)的主动脉环中未观察到这种收缩改变。在猪冠状动脉中也观察到了 GSNO 和
DEA-NO 对收缩的相同不同影响。先前暴露于 100 μM GSNO 而非 100 μM
DEA-NO 的大鼠主动脉环显示 NO 含量(通过 NO 自旋捕获测定)和半胱
氨酸-NO 残基(通过抗半胱
氨酸-NO 抗血清免疫染色测定)持续增加。主动脉组织中由 GSNO 引起的半胱
氨酸-NO 残基的增加可被
硫醇修饰剂对羟基巯基
苯甲酸所阻止。这项研究表明,在离体动脉中,S-
亚硝酸化剂的作用与其他 NO 供体的作用不同。S-亚硝基化剂会引起持续的收缩抑制,这归因于组织
硫醇的 S-亚硝基化作用形成了可释放的 NO 储存。氮氧化物供体的这些不同作用可能对确定其治疗适应症非常重要。