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

Nitric oxide is consumed, rather than conserved, by reaction with oxyhemoglobin under physiological conditions
Nitric oxide is consumed, rather than conserved, by reaction with oxyhemoglobin under physiological conditions
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.
0027-8424
10341-6
Joshi, Mahesh S.
fcd69bea-d53c-4a90-81cd-96ddfbdfe82f
Ferguson, T. Bruce
bec10cc8-ddad-4470-a4eb-451604f893bf
Han, Tae H.
db892c4b-7ce6-4ed7-9240-4888b0e3691d
Hyduke, Daniel R.
64decff6-8028-4472-8b59-f029dcf4a737
Liao, James C.
bd953d33-dc2f-4ae6-8496-7f535159743c
Rassaf, Tienush
a820a375-219a-4fa2-ae10-e77f4b1eb37c
Bryan, Nathan
d6380c2e-70ad-44c5-a783-a2ec3b17c420
Feelisch, Martin
8c1b9965-8614-4e85-b2c6-458a2e17eafd
Lancaster, Jack R.
42f7b1e5-74bf-4e91-b969-960e6e98a85b
Joshi, Mahesh S.
fcd69bea-d53c-4a90-81cd-96ddfbdfe82f
Ferguson, T. Bruce
bec10cc8-ddad-4470-a4eb-451604f893bf
Han, Tae H.
db892c4b-7ce6-4ed7-9240-4888b0e3691d
Hyduke, Daniel R.
64decff6-8028-4472-8b59-f029dcf4a737
Liao, James C.
bd953d33-dc2f-4ae6-8496-7f535159743c
Rassaf, Tienush
a820a375-219a-4fa2-ae10-e77f4b1eb37c
Bryan, Nathan
d6380c2e-70ad-44c5-a783-a2ec3b17c420
Feelisch, Martin
8c1b9965-8614-4e85-b2c6-458a2e17eafd
Lancaster, Jack R.
42f7b1e5-74bf-4e91-b969-960e6e98a85b

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 of the United States of America, 99 (16), 10341-6. (doi:10.1073/pnas.152149699). (PMID:12124398)

Record type: Article

Abstract

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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More information

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

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Local EPrints ID: 337865
URI: http://eprints.soton.ac.uk/id/eprint/337865
ISSN: 0027-8424
PURE UUID: 2ca03de2-cea9-4544-8bec-eab1e0761dba
ORCID for Martin Feelisch: ORCID iD orcid.org/0000-0003-2320-1158

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Date deposited: 22 Jun 2012 13:14
Last modified: 15 Mar 2024 03:41

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Contributors

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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