Heme oxygenase the rate-limiting step in the degradation of heme to bilirubin, generates
carbon monoxide. This gaseous molecule plays important roles in neuronal signaling and
modulation of vascular tone. Additionally, carbon monoxide is involved in some pathological
conditions (eg, ischemia, endotoxic shock, excitotoxicity) as a protective or toxic factor.
Bilirubin, another heme metabolite, exhibits intriguing biological activities as an antioxidant,
an antimutagen, and an anti-complement agent. Vital functions and the dual nature …