Nitrite consumption in ischemic rat heart catalyzed by distinct blood-borne and tissue factors
| Autor: | Valerie Kehoe, Lawrence I. Sinoway, Sophia Scott, Patrick H. McNulty, Mark Kozak, Jinhua Li |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
Male
Erythrocytes Time Factors Xanthine Dehydrogenase Physiology Allopurinol Myocardial Ischemia Myocardial Reperfusion Injury Pharmacology Nitric Oxide Catalysis Nitric oxide Rats Sprague-Dawley Blood cell chemistry.chemical_compound Physiology (medical) medicine Animals Enzyme Inhibitors Nitrite Hypoxia Nitrites Glycogen Myoglobin Myocardium Articles Metabolism Hydrogen-Ion Concentration Rats Disease Models Animal Red blood cell Glucose medicine.anatomical_structure chemistry Biochemistry Circulatory system Cardiology and Cardiovascular Medicine Oxidation-Reduction medicine.drug |
| Zdroj: | American Journal of Physiology-Heart and Circulatory Physiology. 295:H2143-H2148 |
| ISSN: | 1522-1539 0363-6135 |
| Popis: | Nitric oxide (NO) may limit myocardial ischemia-reperfusion injury by slowing the mitochondrial metabolism. We examined whether rat heart contains catalysts potentially capable of reducing nitrite to NO during an episode of regional myocardial ischemia produced by temporary coronary artery occlusion. In intact Sprague-Dawley rats, a 15-min coronary occlusion lowered the nitrite concentration of the myocardial regions exhibiting ischemic glucose metabolism to ∼50% that of nonischemic regions (185 ± 223 vs. 420 ± 203 nmol/l). Nitrite was rapidly repleted during subsequent reperfusion. The heart tissue tested in vitro acquired a substantial ability to consume nitrite when made hypoxic at neutral pH, and this ability was slightly enhanced by simultaneously lowering the pH to 5.5. More than 70% of this activity could be abolished by flushing the coronary circulation with crystalloid to remove trapped erythrocytes. Correspondingly, erythrocytes demonstrated the ability to reduce exogenous nitrite to NO under hypoxic conditions in vitro. In erythrocyte-free heart tissue, the nitrite consumption increased fivefold when the pH was lowered to 5.5. Approximately 40% of this pH-sensitive increase in nitrite consumption could be blocked by the xanthine oxidoreductase inhibitor allopurinol, whereas lowering the Po2 sufficiently to desaturate myoglobin accelerated it further. We conclude that rat heart contains several factors capable of catalyzing ischemic nitrite reduction; the most potent is contained within erythrocytes and activated by hypoxia, whereas the remainder includes xanthine oxidoreductase and other pH-sensitive factors endogenous to heart tissue, including deoxymyoglobin. |
| Databáze: | OpenAIRE |
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