Abstract: Objective To study the relation of renal microvessel cytochrome P450 expression and renal hemodynamics.Methods Compared the difference of renal hemodynamics between late-pregnant and virgin rats,and western blot and HPLC were used to compare the renal microvessel cytochrome P450 expression and activity.Results Comparing with virgin rats,both mean blood pressure and renal vessel resistance decreased in late-pregnant rata(P<0.05),and the renal microvessel cytochrome P450 expression and activity increased.Conclusion These results demonstrated the change of renal hemodynamics in pregnancy might relate to the renal microvessel cytochrome P450 expression