Falsini S, Cellai M P, Angiolini P, Cavuta M, Novelli G P
Istituto di Anestesia e Rianimazione, Università degli Studi di Firenze.
Minerva Anestesiol. 1994 Sep;60(9):413-8.
Reduced Glutathione (GSH) is a well known physiological antioxidant, that would protect against lethal effects of endotoxin. However, the site of the action of GSH can be intracellular (transmembrane passage of constitutive amino acids) or extracellular (membrane thiols).
To search if L-cysteine (one of three constitutive amino acids of GSH) protects against endotoxin as GSH and to search if inhibition of transmembrane passage of GSH and L-cysteine by Probenecid affects that protection.
Rats injected (n = 99) with a lethal dose of endotoxin (BACTO, DIFCO lab. 0111:B4 10 mg/kg ip) immediately after received: (a) Saline solution; (b) GSH 500 mg/kg; (c) L-Cysteine 0.25 g/kg; (d) Probenecid 25 mg/kg in 20% Ethanol plus GSH 500 mg/kg; (e) Probenecid 25 mg/kg in 20% Ethanol; (f) 20% Ethanol. The administration of Saline solution, GSH, L-cysteine was repeated two hours later. Injection volume was 0.5 ml ip. Survival rate of each group of rats was evaluated 6, 12 and 24 hours after endotoxin injection. Survival was compared with that of the control group by Fisher test.
GSH and L-cysteine significantly increase survival if compared to all other treatments (respectively p < 0.002 and p < 0.001 at 12 hours; p < 0.005 and p < 0.0002 at 24 hours). Probenecid nullifies the survival increase caused by GSH. Probenecid alone or Ethanol alone show a survival rate not significantly different in respect to control group.
Protection exerted by GSH against fatal effects of endotoxin is also provided by one of its constituent amino acids (L-cysteine) and is inhibited by Probenecid. So we can infer that such an antioxidant action happens at an intracellular site. Need of high doses of GSH and L-cysteine can be due to the necessity of a strong concentration gradient between extra and intracellular sites.
还原型谷胱甘肽（GSH）是一种众所周知的生理性抗氧化剂，可保护机体免受内毒素的致死作用。然而，GSH的作用位点可能在细胞内（组成型氨基酸的跨膜转运）或细胞外（膜硫醇）。
探究L-半胱氨酸（GSH的三种组成型氨基酸之一）是否像GSH一样能保护机体免受内毒素的侵害，以及丙磺舒对GSH和L-半胱氨酸跨膜转运的抑制是否会影响这种保护作用。
99只大鼠腹腔注射致死剂量的内毒素（BACT0，DIFCO实验室，0111:B4，10mg/kg）后立即接受以下处理：（a）生理盐水；（b）GSH 500mg/kg；（c）L-半胱氨酸0.25g/kg；（d）丙磺舒25mg/kg溶于20%乙醇中加GSH 500mg/kg；（e）丙磺舒25mg/kg溶于20%乙醇中；（f）20%乙醇。两小时后重复给予生理盐水、GSH、L-半胱氨酸。腹腔注射体积为0.5ml。在内毒素注射后6、12和24小时评估每组大鼠的存活率。通过Fisher检验将存活率与对照组进行比较。
与所有其他处理相比，GSH和L-半胱氨酸显著提高了存活率（12小时时分别为p<0.002和p<0.001；24小时时分别为p<0.005和p<0.0002）。丙磺舒消除了GSH引起的存活率提高。单独使用丙磺舒或单独使用乙醇显示出与对照组相比无显著差异的存活率。
GSH对内毒素致死作用的保护作用也由其组成氨基酸之一（L-半胱氨酸）提供，并被丙磺舒抑制。因此我们可以推断这种抗氧化作用发生在细胞内位点。需要高剂量的GSH和L-半胱氨酸可能是由于细胞外和细胞内位点之间需要强大的浓度梯度。
