AIM: To study the effect of dichloromethylene diphos-phonate (DMDP), a selective Kupffer cell toxicant in reference to liver damage and postnecrotic liver regeneration in rats induced by sublethal dose thioacetamide (TA). METHODS: Rats, intravenously (iv ) pre-treated with a single dose of DMDP (10 mg/kg), were intraperitoneally (ip ) injected with TA 6.6 mmol/kg (per 500 mg/kg body weight). Hepatocytes were isolated from rats at 0, 24, 48 and 72 h following TA intoxication and blood and liver samples were obtained. To evaluate the mecha-nisms involved in the postnecrotic regenerative state, DNA distribution and ploidy time course were assayed in isolated hepatocytes. Circulating cytokine tumor necrosis factor-alpha (TNF-α) was assayed in serum and determined by reverse transcriptase-polymerase chain reaction in liver extract. RESULTS: The effect of DMDP induced noticeable changes in postnecrotic regeneration, causing an increased percentage of hepatocytes in the cell cycle S phase. The increase at 24 h in S1 population in rats pretreated with DMDP + TA was significantly (P < 0.05) different compared with that of the TA group (18.07% vs 8.57%). Hepatocytes increased their proliferation as a result of these changes. Also, TNF-α expression and serum level were increased in rats pre-treated with DMDP. Thus, DMDP pre-treatment reduced TA-induced liver injury and accelerated postnecrotic liver regeneration. CONCLUSION: These results demonstrate that Kupffer cells are involved in TA-induced liver, as well as in post-necrotic proliferative liver states. AIM: To study the effect of dichloromethylene diphos-phonate (DMDP), a selective Kupffer cell toxicant in reference to liver damage and postnecrotic liver regeneration in rats induced by sublethal dose thioacetamide (TA). METHODS: Rats, intravenously (iv) treated with a single dose of DMDP (10 mg / kg), were intraperitoneally (ip) injected with TA 6.6 mmol / kg (per 500 mg / kg body weight). Hepatocytes were isolated from rats at 0, 24, 48 and 72 h following evaluation of blood and liver samples were obtained. To evaluate the mecha-nisms involved in the postnecrotic regenerative state, DNA distribution and ploidy time course were assayed in isolated hepatocytes. Circulating cytokine tumor necrosis factor-alpha (TNF-α) was assayed in serum and determined by reverse transcriptase-polymerase chain reaction in liver extract. RESULTS: The effect of DMDP induced noticeable changes in postnecrotic regeneration, causing an increased percentage of hepatocytes in the cell cycle S phase. T he increased at 24 h in S1 population in rats pretreated with DMDP + TA was significantly (P <0.05) different compared with that of the the TA group (18.07% vs 8.57%). Hepatocytes increased their proliferation as a result of these changes. , TNF-α expression and serum level were increased in rats pre-treated with DMDP. Thus, DMDP pre-treatment reduced TA-induced liver injury and accelerated post-tuberculogenic liver regeneration. CONCLUSION: These results demonstrate that Kupffer cells are involved in TA-induced liver, as well as in post-necrotic proliferative liver states.