普洛萨姆对大鼠肝微粒体细胞色素P450 3A酶动力学的影响

Impact of poloxamers on kinetics of CYP3A in rat liver microsomes

关键词:  普洛萨姆  CYP3A  肝微粒体  酶动力学

Key words:  poloxamers  CYP3A  liver microsomes  enzyme kinetics

摘要:

［目的］ 研究普洛萨姆对大鼠肝微粒体细胞色素P450 3A（CYP3A）酶动力学的影响。［方法］ 以CYP3A的探针反应，睾酮6β羟基化反应，来标记CYP3A的活性进行酶动力学体外研究。［结果］ 普洛萨姆浓度在0.1%～0.5%时，大鼠CYP3A活性略升高，但与对照组无显著差异（p>0.05）；当浓度高于0.5%时，能抑制CYP3A活性，且抑制程度随浓度提高而加大。当浓度在0.8%～2%时，CYP3A活性有一定程度降低，但与对照组无显著差异（p>0.05），当浓度高于3%时，能观察到活性被抑制了约27.2%，与对照组比较有显著性差异（p<0.05），当浓度为5％时，抑制百分比已达42.3％。动力学研究表明，0.2%普洛萨姆对CYP3A动力学参数没有显著影响（p>0.05），但是2%普洛萨姆对CYP3A动力学参数有显著影响，V max、S 50、CL均被低估，同时Hill系数被高估。［结论］ 普洛萨姆对大鼠CYP3A活性有浓度依赖性的影响，普洛萨姆在较高浓度能影响CYP3A酶的动力学性质。

Abstract:

［Objective］ To study the impact of poloxamers on the kinetics of CYP3A in rat liver microsomes. ［Methods］ The study of enzyme inhibition kinetics was conducted, utilizing testosterone 6β-hydroxylation as the indication for the activity of CYP3A in rat liver microsomes. ［Results］ In the range of 0.1％～0.5% poloxamers, there was a slight activation of CYP3A activity, but no significant difference was observed compared with control. When the concentration was more than 0.5%, poloxamers exhibited concentration-dependent inhibition on CYP3A activity. In the range of 0.8％～2%, although the activity decreased, no significant inhibition could be observed (p>0.05). However, significant inhibition was observed when the concentration of poloxamers exceeded 3% (p<0.05), and the CYP3A activity decreased by 42.3% at 5% polpxamers. The further kinetics study showed that 0.2% poloxamers did not affect the kinetics parameters of CYP3A (p>0.05), but 2% poloxamers significantly affected the evaluation of kinetics parameters of CYP3A (p<0.05), and resulted in underestimation of V max, S 50, CL and overestimation of Hill coefficient. ［Conclusions］ Poloxamers may concentration-dependently influence CYP3A activity and the kinetics properties of CYP3A.