Chronic exercise downregulates myocardial myoglobin and attenuates nitrite reductase capacity during ischemia-reperfusion

• Type of Material: Article
• Authors: Chad K. Nicholson, Emory University; Jonathan P. Lambert, Emory University; Chi-Wing Chow, Albert Einstein College of Medicine; David J. Lefer, Emory University; John W Calvert, Emory University
• Language: English
• Date: 2013-11-01
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2013 Elsevier Ltd. All rights reserved.
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1016/j.yjmcc.2013.08.002
• Title of Journal or Parent Work: Journal of Molecular and Cellular Cardiology
• ISSN: 0022-2828
• Volume: 64
• Start Page: 1
• End Page: 10
• Grant/Funding Information: This work was also supported by funding from the Carlyle Fraser Heart Center (CFHC) of Emory University Hospital Midtown.; Supported by grants from the American Diabetes Association (7-09-BS-26); and the National Institutes of Health National Heart Lung and Blood Institute (NHLBI) (5R01HL098481-03) to J.W.C.;and (5R01HL092141), (5R01HL093579), (1U24HL 094373), and (1P20HL113452) to D.J.L.
• Keywords: OXIDE; Cardiac & Cardiovascular Systems; Nitric oxide; IN-VIVO; CALCINEURIN; Science & Technology; Nitrite; MEDIATED CARDIOPROTECTION; HYPERTROPHIC CARDIOMYOPATHY; Life Sciences & Biomedicine; Myoglobin; SKELETAL-MUSCLE; DEFICIENT MICE; Calcineurin/NFAT signaling; Cell Biology; DEPENDENT TRANSCRIPTIONAL PATHWAY; CARDIAC-HYPERTROPHY; Cardiovascular System & Cardiology; Exercise; Myocardial ischemia-reperfusion; HEART-FAILURE
• Research Categories: Health Sciences, Medicine and Surgery; Biology, Cell

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 4. weeks displayed an 18% reduction in infarct size when compared to sedentary mice, whereas mice administered nitrite therapy (25. mg/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.