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Nitric oxide is consumed, rather than conserved, by reaction with oxyhemoglobin under physiological conditions

Joshi, Mahesh S., Ferguson, T. Bruce, Han, Tae H., Hyduke, Daniel R., Liao, James C., Rassaf, Tienush, Bryan, Nathan, Feelisch, Martin and Lancaster, Jack R. (2002) Nitric oxide is consumed, rather than conserved, by reaction with oxyhemoglobin under physiological conditions Proceedings of the National Academy of Sciences, 99, (16), pp. 10341-6. (doi:10.1073/pnas.152149699). (PMID:12124398).

Record type: Article


Although irreversible reaction of NO with the oxyheme of hemoglobin (producing nitrate and methemoglobin) is extremely rapid, it has been proposed that, under normoxic conditions, NO binds preferentially to the minority deoxyheme to subsequently form S-nitrosohemoglobin (SNOHb). Thus, the primary reaction would be conservation, rather than consumption, of nitrogen oxide. Data supporting this conclusion were generated by using addition of a small volume of a concentrated aqueous solution of NO to a normoxic hemoglobin solution. Under these conditions, however, extremely rapid reactions can occur before mixing. We have thus compared bolus NO addition to NO generated homogeneously throughout solution by using NO donors, a more physiologically relevant condition. With bolus addition, multiple hemoglobin species are formed (as judged by visible spectroscopy) as well as both nitrite and nitrate. With donor, only nitrate and methemoglobin are formed, stoichiometric with the amount of NO liberated from the donor. Studies with increasing hemoglobin concentrations reveal that the nitrite-forming reaction (which may be NO autoxidation under these conditions) competes with reaction with hemoglobin. SNOHb formation is detectable with either bolus or donor; however, the amounts formed are much smaller than the amount of NO added (less than 1%). We conclude that the reaction of NO with hemoglobin under normoxic conditions results in consumption, rather than conservation, of NO.

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e-pub ahead of print date: 17 July 2002
Published date: 6 August 2002
Organisations: Clinical & Experimental Sciences


Local EPrints ID: 337865
ISSN: 0027-8424
PURE UUID: 2ca03de2-cea9-4544-8bec-eab1e0761dba
ORCID for Martin Feelisch: ORCID iD

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Date deposited: 22 Jun 2012 13:14
Last modified: 18 Jul 2017 06:00

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Author: Mahesh S. Joshi
Author: T. Bruce Ferguson
Author: Tae H. Han
Author: Daniel R. Hyduke
Author: James C. Liao
Author: Tienush Rassaf
Author: Nathan Bryan
Author: Martin Feelisch ORCID iD
Author: Jack R. Lancaster

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