Affiliation:
1. NMR Laboratory for Physiological Chemistry, Division of Cardiovascular Medicine (R.T., J.D.A.), and the Research Division (N.M., M.F.H., L.J.G.), Joslin Diabetes Center, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Mass.
Abstract
Background
Recent reports suggest that activation of adenosine monophosphate (AMP)–activated protein kinase (AMPK), in response to acute changes in cellular energy status in cardiac and skeletal muscles, results in altered substrate utilization. We hypothesized that chronic alterations in myocardial energetics in hypertrophied hearts (left ventricular hypertrophy, LVH) will lead to elevated AMPK activity, which in turn regulates substrate utilization.
Methods and Results
Using
31
P NMR spectroscopy and biochemical assays, we found that in LVH hearts, adenosine triphosphate (ATP) concentration decreased by 10%, phosphocreatine concentration decreased by 30%, and total creatine concentration was unchanged. Thus, the ratio of phosphocreatine/creatine decreased to one third of controls, and the ratio of AMP/ATP increased to 5 times above controls. These changes were associated with increased α
1
and α
2
AMPK activity (3.5- and 4.8-fold above controls, respectively). The increase in AMPK α
1
activity was accompanied by a 2-fold increase in α
1
expression, whereas α
2
expression was decreased by 30% in LVH. The basal rate of 2-deoxyglucose uptake increased by 3-fold in LVH, which was associated with an increased amount of glucose transporters present on the plasma membrane.
Conclusions
These results demonstrate for the first time that chronic changes in myocardial energetics in hypertrophied hearts are accompanied by significant elevations in AMPK activity and isoform-specific alterations in AMPK expression. It also raises the possibility that AMPK signaling plays an important role in regulating substrate utilization in hypertrophied hearts.
Publisher
Ovid Technologies (Wolters Kluwer Health)
Subject
Physiology (medical),Cardiology and Cardiovascular Medicine
Cited by
262 articles.
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