title: Chronic exercise downregulates myocardial myoglobin and attenuates nitrite reductase capacity during ischemia-reperfusion.
abstract: The infarct sparing effects of exercise are evident following both long-term and short-term training regimens. Here we compared the infarct-lowering effects of nitrite therapy, voluntary exercise, and the combination of both following myocardial ischemia-reperfusion (MI/R) injury. We also compared the degree to which each strategy increased cardiac nitrite levels, as well as the effects of each strategy on the nitrite reductase activity of the heart. Mice subjected to voluntary wheel running (VE) for 4weeks displayed an 18% reduction in infarct size when compared to sedentary mice, whereas mice administered nitrite therapy (25mg/L in drinking water) showed a 53% decrease. However, the combination of VE and nitrite exhibited no further protection than VE alone. Although the VE and nitrite therapy mice showed similar nitrite levels in the heart, cardiac nitrite reductase activity was significantly reduced in the VE mice. Additionally, the cardiac protein expression of myoglobin, a known nitrite reductase, was also reduced after VE. Further studies revealed that cardiac NFAT activity was lower after VE due to a decrease in calcineurin activity and an increase in GSK3β activity. These data suggest that VE downregulates cardiac myoglobin levels by inhibiting calcineurin/NFAT signaling. Additionally, these results suggest that the modest infarct sparing effects of VE are the result of a decrease in the hearts ability to reduce nitrite to nitric oxide during MI/R.
authors: Department of Surgery, Division of Cardiothoracic Surgery, Carlyle Fraser Heart Center, Emory University School of Medicine, Atlanta, GA 30308, USA.
authors: Chad K
authors: CK
authors: Nicholson
authors: Jonathan P
authors: JP
authors: Lambert
authors: Chi-Wing
authors: CW
authors: Chow
authors: David J
authors: DJ
authors: Lefer
authors: John W
authors: JW
authors: Calvert
mesh_terms: D000818:Animals; D002316:Cardiotonic Agents / Q000008:administration & dosage; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008840:Microfilament Proteins; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism; D015428:Myocardial Reperfusion Injury / Q000188:drug therapy / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D009211:Myoglobin / Q000235:genetics* / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D009572:Nitrite Reductases / Q000378:metabolism*; D009573:Nitrites / Q000008:administration & dosage / Q000378:metabolism; D010805:Physical Conditioning, Animal
chemical_list: D002316:Cardiotonic Agents; D002352:Carrier Proteins; D008840:Microfilament Proteins; D009124:Muscle Proteins; D009211:Myoglobin; C523646:Myoz2 protein, mouse; D009573:Nitrites; D009569:Nitric Oxide; D009572:Nitrite Reductases; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D038362:Glycogen Synthase Kinase 3
keywords: Calcineurin/NFAT signaling; Exercise; Myocardial ischemia–reperfusion; Myoglobin; Nitric oxide; Nitrite
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