Nitric Oxide (NO) is a gas that has multiple signalling and effector functions in mammalian tissues. Hemoglobin scavanges NO and this limits NO's biological activity; conversely, it has recently been proposed that reversible NO binding to the beta- globin cysteine 93 is allosterically linked to oxygenation and this contributes to the control of oxygen delivery in tissues. We have investigated NO transport and metabolism by hemoglobin in human subjects in vitro and in vivo. We have developed new, highly sensitive chemical and spectrophotometric assays for S- nitrosohemoglobin (SNO-Hb) and nitrosyl (heme) hemoglobin (Hb-Fe II-NO). We find that inhalation of NO by normal subjects leads to formation of significant amounts of iron-nitrosylated hemoglobin and of nitrite, with large arteriovenous gradients, suggesting that one or both of these species could deliver NO. We find that NO inhalation, after inhibition of local NO synthesis, causes peripheral (arm) increases in blood flow in normal individuals but not in sickle cell patents. The results in normal volunteers confirm that NO can be transported as a hormone and thus has the potential to be a pharmacological agent (i.e., a drug). We believe that the lack of effect in the sickle cell patients is due to the presence of circulating hemoglobin and that this contributes to the pathophysiology of this and other chronic and acute hemolytic syndromes. In more recent studies we have infused nitrite into the brachial arteries of normal humanb volunteers and have shown that this increases blood flow, suggesting that nitrite could function physiologically as a source of NO and could be used pharmacologically. We find that in vitro deoxyerythrocytes and nitrite cause aortic ring preparations to dilate, suggesting a mechanism of nitrite activation by deoxyheme proteins. We also find that nitrite inhalalation in hypoxic newborn sheep lead to decreased pulmonary artery pressures and exhalation of NO; nitrite infusions in these animals leads to decreases in mean arterial blood pressure. We are currently studying the formation and compartmentalization of nitrite in the blood, in erythrocytes in particular, and whether nitrite levels may be a marker of cadiovascular risk in humans. These studies are designed to allow us to study nitrite infusions in normal human subjects and those with a variety of ischemic (including sickle cell anemia) diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Intramural Research (Z01)
Project #
1Z01DK025093-06
Application #
6983681
Study Section
(LCB)
Project Start
Project End
Budget Start
Budget End
Support Year
6
Fiscal Year
2004
Total Cost
Indirect Cost
Name
U.S. National Inst Diabetes/Digst/Kidney
Department
Type
DUNS #
City
State
Country
United States
Zip Code
Deans, Katherine J; Minneci, Peter C; Suffredini, Anthony F et al. (2007) Randomization in clinical trials of titrated therapies: unintended consequences of using fixed treatment protocols. Crit Care Med 35:1509-16
Power, Gordon G; Bragg, Shannon L; Oshiro, Bryan T et al. (2007) A novel method of measuring reduction of nitrite-induced methemoglobin applied to fetal and adult blood of humans and sheep. J Appl Physiol 103:1359-65
Crawford, Jack H; Isbell, T Scott; Huang, Zhi et al. (2006) Hypoxia, red blood cells, and nitrite regulate NO-dependent hypoxic vasodilation. Blood 107:566-74
Holly, M K; Dear, J W; Hu, X et al. (2006) Biomarker and drug-target discovery using proteomics in a new rat model of sepsis-induced acute renal failure. Kidney Int 70:496-506
Pelletier, Mildred M; Kleinbongard, Petra; Ringwood, Lorna et al. (2006) The measurement of blood and plasma nitrite by chemiluminescence: pitfalls and solutions. Free Radic Biol Med 41:541-8
Kim-Shapiro, Daniel B; Schechter, Alan N; Gladwin, Mark T (2006) Unraveling the reactions of nitric oxide, nitrite, and hemoglobin in physiology and therapeutics. Arterioscler Thromb Vasc Biol 26:697-705
Kleinbongard, Petra; Dejam, Andre; Lauer, Thomas et al. (2006) Plasma nitrite concentrations reflect the degree of endothelial dysfunction in humans. Free Radic Biol Med 40:295-302
Huang, Zhi; Shiva, Sruti; Kim-Shapiro, Daniel B et al. (2005) Enzymatic function of hemoglobin as a nitrite reductase that produces NO under allosteric control. J Clin Invest 115:2099-107
Piknova, Barbora; Gladwin, Mark T; Schechter, Alan N et al. (2005) Electron paramagnetic resonance analysis of nitrosylhemoglobin in humans during NO inhalation. J Biol Chem 280:40583-8
Minneci, Peter C; Deans, Katherine J; Zhi, Huang et al. (2005) Hemolysis-associated endothelial dysfunction mediated by accelerated NO inactivation by decompartmentalized oxyhemoglobin. J Clin Invest 115:3409-17

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