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. Author manuscript; available in PMC: 2011 Jan 1.
Published in final edited form as: Periodontol 2000. 2010 Feb;52(1):94–116. doi: 10.1111/j.1600-0757.2009.00329.x

Fig. 1. Availability of hemin in physiological conditions.

Fig. 1

Upon vascular trauma, red blood cells (RBC) are released. Following RBC lysis, hemoglobin (Hb) is released. The released hemoglobin is rapidly bound by haptoglobin (Hp) and the complex is transported to the liver. This is the major hemin pathway. Upon depletion of Hp-binding capacity, hemoglobin degrades and the released hemin is bound by a high affinity serum protein, hemopexin (Hpx), and transported to the liver. Any remaining free hemin is bound by a lower affinity protein, albumin. The hemin-albumin complexes can also be bound by hemopexin and the heme-Hpx complexes can be transported to the liver.