NOS2 and Sepsis: The strong link between BH4 levels and inflammation (necessary to provide enough BH4 for iNOS activity) was evident from previously reported HPLC/ECD data in septic mice, where plasma BH4 levels increased from 40 to 150 nM within 6 h after induction of sepsis with a subsequent decrease to 70 nM within 24 h after induction of sepsis [22].