Moffat J A, Armstrong P W, Marks G S
Can J Physiol Pharmacol. 1982 Oct;60(10):1261-6. doi: 10.1139/y82-185.
The mechanism by which nitroglycerin (GTN) initiates relaxation in vascular smooth muscle is not known. According to one hypothesis a specific nitrate receptor exists with a key sulfhydryl (SH) group in the active site. The current study was performed with sulfhydryl reagents in helical strips of the canine medial saphenous vein from 20 dogs to examine the role of the SH group in the action of GTN. The reagents used were 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) and p-chloromercuribenzoate (PCMB) which bind to and inactivate SH groups, and dithiothreitol (DTT), an SH reducing agent. It was anticipated that DTNB and PCMB would decrease the sensitivity to GTN while DTT might increase the sensitivity to GTN. Treatment of strips with PCMB and DTNB did not alter the dose-response curves for GTN. In contrast, following DTT treatment (1 x 10(-4)M) the maximum response to GTN (10(-5)M) was significantly reduced from 80.3% +/- 4.0 (SD) in control strips to 46.9% +/- 4.4 (SD) in the treated strips. These data suggest that relaxation induced by GTN in vascular smooth muscle occurs by a mechanism other than interaction with membrane SH groups.
硝酸甘油（GTN）引发血管平滑肌舒张的机制尚不清楚。根据一种假说，存在一种特定的硝酸盐受体，其活性位点有一个关键的巯基（SH）基团。本研究使用巯基试剂对20只犬的内侧隐静脉螺旋条进行实验，以研究SH基团在GTN作用中的作用。所用试剂为5,5'-二硫代双（2-硝基苯甲酸）（DTNB）和对氯汞苯甲酸（PCMB），它们可与SH基团结合并使其失活，以及二硫苏糖醇（DTT），一种SH还原剂。预计DTNB和PCMB会降低对GTN的敏感性，而DTT可能会增加对GTN的敏感性。用PCMB和DTNB处理条带并未改变GTN的剂量反应曲线。相反，在DTT处理（1×10⁻⁴M）后，对GTN（10⁻⁵M）的最大反应从对照条带中的80.3%±4.0（标准差）显著降低至处理条带中的46.9%±4.4（标准差）。这些数据表明，GTN在血管平滑肌中诱导的舒张是通过与膜SH基团相互作用以外的机制发生的。
