Wright R O, Woolf A D, Shannon M W, Magnani B
Department of Medicine, Harvard University Medical School, Children's Hospital, Boston, MA, USA.
Acad Emerg Med. 1998 Mar;5(3):225-9. doi: 10.1111/j.1553-2712.1998.tb02617.x.
To determine whether N-acetylcysteine (NAC) reduces methemoglobin (MHB) in an in-vitro model of glucose-6-phosphate dehydrogenase (G6PD) deficiency, given that methylene blue is an ineffective MHB antidote in G6PD deficiency.
Five volunteers donated blood, which was divided equally into 2 test tubes, centrifuged, and washed with Tris-Mopps buffer (pH 7.4, 15 mmol/L glucose). Both tubes were incubated with epiandrosterone (EA) (400 micromol), a specific inhibitor of G6PD. After 75 microL of 0.18 mol hydroxylamine (HA) was added to induce MHB formation, 150 microL of NAC (20 mg/mL) was added to tube 1 and 150 microL of phosphate-buffered saline (PBS) was added to tube 2 as a volume control. Serial MHB levels are reported as a percentage of total hemoglobin (Hb). G6PD activity was measured at baseline, 15 minutes after EA, and at 5 hours.
Mean G6PD activity at baseline was 9.2+/-2.9 U/g Hb (normal >4.6 U/g Hb); 15 minutes after EA was 3.0+/-1.0 U/g Hb; and at experiment's end was 2.3+/-0.7 U/g Hb. The mean (+/-SD) areas under the concentration-time curves (AUCs) of NAC-EA-HA and PBS-EA-HA samples were compared using an unpaired t-test and were significantly different: PBS-EA-HA, 20,400+/-1,100 % min, vs NAC-EA-HA, 10,400+/-1,000 % min, respectively (p < 0.05).
In this in-vitro model of G6PD deficiency, NAC efficiently reduced MHB.
鉴于亚甲蓝在葡萄糖-6-磷酸脱氢酶（G6PD）缺乏症中作为高铁血红蛋白（MHB）解毒剂无效，本研究旨在确定N-乙酰半胱氨酸（NAC）在G6PD缺乏症的体外模型中是否能降低MHB。
5名志愿者献血，血液等分为2支试管，离心后用Tris-Mopps缓冲液（pH 7.4，15 mmol/L葡萄糖）洗涤。两支试管均与G6PD的特异性抑制剂表雄酮（EA）（400 μmol）一起孵育。在加入75 μL 0.18 mol羟胺（HA）以诱导MHB形成后，向试管1中加入150 μL NAC（20 mg/mL），向试管2中加入150 μL磷酸盐缓冲盐水（PBS）作为体积对照。系列MHB水平以总血红蛋白（Hb）的百分比报告。在基线、EA后15分钟和5小时测量G6PD活性。
基线时平均G6PD活性为9.2±2.9 U/g Hb（正常>4.6 U/g Hb）；EA后15分钟为3.0±1.0 U/g Hb；实验结束时为2.3±0.7 U/g Hb。使用非配对t检验比较NAC-EA-HA和PBS-EA-HA样品的浓度-时间曲线（AUC）下的平均（±标准差）面积，两者有显著差异：PBS-EA-HA分别为20400±1100%·min，NAC-EA-HA为10400±1000%·min（p<0.05）。
在该G6PD缺乏症的体外模型中，NAC能有效降低MHB。
