Objective To measure the effect of panax notoginseng saponins (PNS) on renal cortical tubule cell apoptosis and apoptosis-related genes in early stage after renal trauma and to investigate the protective mechanism of PNS for renal trauma.Methods Seventy-eight Wistar rats were divided into trauma group (n =36),trauma + treatment group (treatment group,n =36),normal control group (control group,n =6) according to the random number table.In treatment group,rats received intraperitoneal administration of PNS (70 mg/kg).Instead,substitute of an equal dose of isotonic saline was used for the rats in trauma and normal control groups.Trauma and treatment groups were subdivided at 1,6,12,24,36 and 48 hours posttrauma,with 6 rats per group.The kidney specimens were extracted at each time point to detect Bax expression in the cortex with immunohistochemistry and in situ hybridization histochemistry.Moreover,the positive expression of Bax was compared among groups and its variation regularity with time were detected.Results In trauma group,mRNA transcription of pro-apoptosis gene Bax increased at 12 hours in the superficial cortex,but increased at 1 hour in deep cortex; protein expression of pro-apoptosis factor Bax showed no apparent reduction within 36 hours in the superficial cortex,but evident decrease within 12 hours in the deep cortex.In treatment group,mRNA transcription of pro-apoptosis gene Bax decreased immediately after treatment in the renal cortex and lasted until 48 h; protein expression of pro-apoptosis factor Bax showed unidirectional reduction until 48 h in the renal cortex.Conclusion PNS inhibits cell apoptosis by down-regulating the mRNA and protein expression of Bax.