生理溶液中硝普钠释放一氧化氮巯基通路的动力学研究

Studies on kinetics of nitric oxide released from sodium nitroprusside

目的 探索台氏液中一氧化氮供体硝普钠 (SNP)在含活性巯基化合物催化下释放一氧化氮 (NO)的动力学特征 ,为体外NO药理作用定量研究提供实验依据。方法 在 37℃恒温避光条件下 ,对NO特异氧化产物NO- 2 以Griess试剂还原显色 ,采用分光光度法 ,比较分别有半胱氨酸 (CYS)、谷胱甘肽 (GSH)、巯基乙醇、青霉胺 (PCA)、N 乙酰半胱氨酸 (NAC)等 5种巯基化合物存在的台氏液中 ,SNP释放NO的情况 (n =3)。结果 2 4 0min内 ,在分别含有 2 5mmol·L- 1 各种巯基试剂的测试系统中 ,有CYS存在时 ,SNP释放NO呈一级动力学 ,速率常数K =0 .1 66 3min- 1 (r =0 .92 6 3) ,稳态浓度为 1 .0 2mmol·L- 1 ;有GSH存在时 ,NO释放呈多相性 ,2 5min达峰值 ,为 0 .53mmol·L- 1 ,1 80min后渐成 0 .36mmol·L- 1 的稳态 ;有巯基乙醇存在时 ,NO释放呈多相反应 ,60min达峰值 ,为 0 .1 1mmol·L- 1 ,1 2 0min后渐成 0 .0 9mmol·L- 1 的稳态 ;有PCA存在时 ,NO的释放成线性 ,释放公式为 :CtPCA=0 .0 742 +0 .0 0 0 2t (r =0 .9979) ;在有NAC存在的测试系统中 ,未测出有NO释放。结论 恒温避光台氏液中 ,SNP通过巯基通路释放NO的动力学特征受到巯基化合物自身的化学结构及空间位置的影响 ;2 4

OBJECTIVE: To investigate the kinetic characteristics of nitric oxide (NO) released from sodium nitroprusside (SNP) in Tyrode solution. METHOD: Griess assay was used to measure NO releasing from SNP. Five thiol-containing compounds (CYS, GSH, PCA, NAC, mercapto ethanol) in Tyrode solution were compared while protected from light at 37°C by spectrophotometry. RESULTS: For every thiol-containing compounds at 25 mmol&middotL-1 in Tyrode solutions over 240 min, NO was released in a first-order rate by CYS, K = 0. 166 3 min-1 (r = 0. 926 3), the steady state concentration was 1.02 mm&middotL-1. The releasing pathway of NO from SNP in Tyrode with 25 mmol&middotL-1 GSH appeared multiple phase reactions with the peak value of 0.53 mmol&middotL-1 and steady state value of 0.36 mmol&middotL-1 after 180 min. The same pathway appeared when 25 mmol&middotL-1 mercapto ethanol was used, but the peak and steady state value were 0.11 mmol&middotL-1 and 0.09 mmol&middotL-1 respectively. NO was generated from SNP by PCA in a zero-order rate and the linear equation was CtPCA = 0.0742+0.0002 t (r = 0. 9979). NO could not be detected in the system with 25 mmol&middotL-1 NAC. CONCLUSION: Under 37°C and protected from light, the kinetics of NO released from SNP was significantly influenced by the construction and spatial structure of thiols. The generation of NO from different thiol-containing compounds at 25 mmol&middotL-1 was successively CYS>GSH>mercapto>GSH>rnercapto ethanol>PCA>NAC.