Abstract: AIM: To study the methodology of hepatic cytochromes P450 in Wistar rats. METHODS: After the Wistar rats were administered with gatifloxacin and ciprofloxacin once daily for 7 days, and liver microsome was distilled by different velocity centrifugation.The Lowry method was used to measure the concentration of protein in liver microsome, and the activities of gatifloxacin in hepatic microsomal enzymes (CYP450)of rats were studied by spectrophotometer. RESULTS: The linearity range of ox blood serum albumin standard curve was 25-250 mg·L^-1 with the detection limits 25 mg·L^-1 and correlation coefficient 0.9988.The contents of cytochromes P450 and cytochromes b5 and the activity of NADPH-cytochrome C reductase indicated that ultraviolet spectrophotometer method was sensitive.The linearity range of formaldehyde standard curve, which was used to measure the activities of aminopyrine-N-demethylase and erytheomycin-N-demethylase was 0.05-0.5 mmol ·L^-1 with the detection limits 0.05mmol·L^-1 and correlation coefficient 0.9998.The linearity range of resorufin standard curve, which was used to measure the activity of Coumarin 7-hydroxylation was 1-8 μmol·L^-1 with the detection limits 1 μmol·L^-1 and correlation coefficient 0.9998. CONCLUSION: The methods of measuring the contents and activities of the six hepatic microsomal enzymes are sensitive and credible in Wistar rats by ultraviolet and fluorescence spectrophotometer.

Key words: ultraviolet spectrophotometer, fluorescence spectrophotometer, cytochromes P450