Arginase activity is inhibited by L-NAME, both in vitro and in vivo.

The present study investigated the ability of the arginine analog L-NAME (N(omega)-Nitro-L-arginine methyl ester) to modulate the activity of arginase. L-NAME inhibited the activity of arginase in lysates from rat colon cancer cells and liver. It also inhibited the arginase activity of tumor cells in culture. Furthermore, in vivo treatment of rats with L-NAME inhibited arginase activity in tumor nodules and liver, and the effect persisted after treatment ceased. The effect of L-NAME on arginase requires consideration when it is used in vivo in animal models with the aim of inhibiting endothelial NO-synthase, another enzyme using arginine as substrate.