草鱼肝细胞中恩诺沙星脱乙基代谢的酶动力学

Enzymatics on deethylation metabolism of enrofloxacin in grass carp hepatocyte

用RP-HPLC法检测了草鱼肝细胞系（GCL）细胞中恩诺沙星（ENR）的代谢情况,结果显示,药物利福平（RIF）和苯巴比妥（PB）在浓度分别为（12.6±0.9）μM和（34.8±3.6）μM时对ENR脱乙基酶具有最大的诱导倍数,分别为6.0±0.4和2.3±0.3;而红霉素（ERM）对ENR脱乙基酶具有抑制作用,其抑制剂浓度EC50为（20.3±1.8）μM。RIF诱导组和对照组的GCL细胞中ENR代谢的药时曲线方程分别为Ct/Co=-0.0654Ln（t）＋0.7342和Ct/Co=-0.0280Ln（t）＋0.9300,酶动力学方程分别为1/V=72.5530×1/[S]＋1.4922和1/V=530.9800×1/[S]＋3.5274。ENR消除率和环丙沙星（CIP）转化率的研究结果表明,RIF对ENR的脱乙基代谢具有显著的促进作用,而酶动力学参数表明,RIF诱导的酶与底物的亲合力较高,酶促反应的强度较大。

Enrofloxacin （ENR） and its metabolite ciprofloxacin （CIP） in GCL cells were determined by RP-HPLC. ENR- deethylase activity was figured by the rate of CIP production. Refampicin （RIF） and phenobarbital （PB） enhanced the activity with maximal multiples of 6.0±0.4 and 2.3±0.3 at （ 12.6±0.9）μM and （34.8 ±3.6）μM as EC100, respectively. On the contrary, erythromycin （ERM） depressed it and the EC50 of inhibition was （20.3±1.8）μM. The concentration-time equations of ENR metabolism in RIF-treated and control group were Ct/Co = -0.0654Ln（ t ） ＋ 0.7342 and Ct/Co = -0.0280Ln（ t ） ＋ 0.9300, respectively. After metabolism for 12h in either group, the ratio of ENR elimination were 41.2%±3.4% and 15.3%±4.2% respectively, and the ratio of ENR-deethylation to CIP were 78.9%±8. 7% and 51.8%±4.2% respectively. The enzymatic equations in these two group were 1/V = 72.5530×1/[ S ] ＋ 1.4922 and 1/V = 530.9800×1/[ S] ＋ 3.5274, respectively. ENR-deethylase induced by RIF has higher affinity with substrate and stronger potency to catalyze deethylation than the control.