Carbon monoxide physiological roles

Choi, A.M.K., Otterbein, L.E. (2002). Emerging role of carbon monoxide in physiologic and pathophysiologic states. Anti-oxid. Redox Signal. 4 227-8. 

Ingi, T., Ronnett, G.V. (1995). Direct demonstration of a physiological role for carbon monoxide in olfactory receptor neurons. 

Surprising perhaps, carbon monoxide is produced in the body as a result of the normal breakdown of haemoglobin from red blood cells. The enzyme, haem oxygenase, converts the haem group into bilirubin and releases CO into solution. Current research has even suggested that trace amounts of CO may have a physiological role, possibly acting as a neuromodulator. 

Root, W.S., 1965. Carbon monoxide. In Fenn, W.O., Rahn, H. (Eds.), Handbook of Physiology American Physiological Society, Washington, DC, pp. 1078-1098. Rosenberg, A.A., Harris, A.R, Koehler, R.C., et al., 1986. Role of 02-hemoglobin affinity in the regulation of cerebral blood flow in fetal sheep. Am. J. Physiol. 

Appreciation of the functional role(s) of these mitochondrial systems on a physiological (or organ) level awaits further investigations. It would be of great interest to know the effects of hypoxia (e.g., high altitude) and chronic carbon monoxide poisoning on the heart mitochondrial fetty acid synthetic activity. 

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