Figure 5.

Arginase-related toxicity was found in mice treated at doses of 15 mg/kg or greater. On necropsy, the only evidence of normal tissue toxicity was massive bone marrow devastation (A), whereas control bone marrow remained normal (B). In addition, weight loss was measured as a function of dose-dependent toxicity (0–32 mg/kg, n = 5 each) after IP injection of l-arg. The greatest observed weight loss occurred 4 days after treatment (C). The 16- and 32-mg/kg groups had a BCS of 1 and were killed for humane reasons. The mice in the 8-mg/kg group had a BCS score of 2 to 3 and regained their original body mass in an additional 2 to 3 days.