Deoxygenated/oxygenated hemoglobin, under the influence of specific chemical agents, is changed into derivatives: methemoglobin, S-nitrosohemoglobin, carbonous oxide hemoglobin, sulphhemoglobin, cyanomethemoglobin .
The reaction of binding nitrogen oxide to hemoglobin comprises S-nitrolisation of Cys93 residue in the beta-globin chain and formation of S-nitrosohemoglobin (HbSNO) .
(1), (2) They also report that when RBCs leave the body during blood-banking donations, nitric-oxide bioactivity and S-nitrosohemoglobin in RBCs begin breaking down almost immediately.
Investigators are suggesting that renitrosylation--adding a purified aqueous solution of nitric-oxide gas into banked blood before transfusions--can raise the concentration of S-nitrosohemoglobin in vitro which, in turn, can amplify vasodilation in vivo.
Hemoglobin-S does not transfer nitric oxide from heme to thiol as well as normal hemoglobin during S-nitrosohemoglobin conformation The symptoms of sickle-cell disease are attributed to the physical obstruction of blood vessels by distorted or sickled and rigid RBCs.
Investigators at DUMC have shown that the level of S-nitrosohemoglobin was reduced by 85% to 95% at storage days seven and 43 compared to day one.
Investigators have demonstrated that replenishing banked blood with nitric- oxide gas raises S-nitrosohemoglobin, or SNO-Hb, concentrations and restores the hypoxic vasodilatory activity of RBCs.
(17) There exist opportunities to further investigate nitric-oxide bioactivity as suggested by Bonaventura which include testing of arterial and venous RBC S-nitrosohemoglobin as a diagnostic indicator for transfusion; assaying hemoglobin re-nitrosylation treatment of stored RBCs; verification of normalized RBC rheology before transfusions; and verification of normalized RBC vasoactivity prior to transfusion.
Thus, further research is needed to measure the effectiveness of transfusions by testing the concentration of nitric oxide in the form of S-nitrosothiols or S-nitrosohemoglobin in the peripheral blood of patients who receive blood transfusions.
S-Nitrosohemoglobin deficiency: A mechanism for loss of physiological activity in banked blood.In: Proceedings of the National Academy of Science (PNAS).