Cell-free hemoglobin, released from the red cell, may play a major role in regulating the
bioavailability of nitric oxide. The abundant serum protein haptoglobin, rapidly binds to free
hemoglobin forming a stable complex accelerating its clearance. The haptoglobin gene is
polymorphic with two classes of alleles denoted 1 and 2. We have previously demonstrated
that the haptoglobin 1 protein–hemoglobin complex is cleared twice as fast as the
haptoglobin 2 protein–hemoglobin complex. In this report, we explored whether haptoglobin …