Changes of nitric oxide synthase activity and free methylarginines contents in regenerating rat liver after partial hepatectomy

In the present study, liver regeneration rate (%) was increased up to 70% 3 days after partial hepatectomy (PH). Nitric oxide synthase (NOS) activity in liver tissue as well as serum nitrite/ nitrate content had no timed response, revealing no significant difference between sham-operated and partially hepatectomized rat liver. Contents of free methylarginines in liver tissue were increased biphasically in a time-dependent manner after PH. However, those in serum did not exhibit the same patterns as in liver. Taken together, the results suggest that N^G-monomethyl-L-arginine (MMA) and N^G, N^G-dimethylarginine (DMA) play a role in inhibiting nitric oxide (NO) synthesis in regenerating rat liver because the increase of their contents was synchronized with NOS expression.