AMP-activated protein kinase mediates ischemic glucose uptake and prevents postischemic cardiac dysfunction, apoptosis, and injury.
AMP-activated protein kinase (AMPK) is an important regulator of diverse cellular pathways in the setting of energetic stress. Whether AMPK plays a critical role in the metabolic and functional responses to myocardial ischemia and reperfusion remains uncertain. We examined the cardiac consequences of long-term inhibition of AMPK activity in transgenic mice expressing a kinase dead (KD) form of the enzyme. The KD mice had normal fractional shortening and no heart failure, cardiac hypertrophy, or fibrosis, although the in vivo left ventricular (LV) dP/dt was lower than that in WT hearts. During low-flow ischemia and postischemic reperfusion in vitro, KD hearts failed to augment glucose uptake and glycolysis, although glucose transporter content and insulin-stimulated glucose uptake were normal. KD hearts also failed to increase fatty acid oxidation during reperfusion. Furthermore, KD hearts demonstrated significantly impaired recovery of LV contractile function during postischemic reperfusion that was associated with a lower ATP content and increased injury compared with WT hearts. Caspase-3 activity and TUNEL-staining were increased in KD hearts after ischemia and reperfusion. Thus, AMPK is responsible for activation of glucose uptake and glycolysis during low-flow ischemia and plays an important protective role in limiting damage and apoptotic activity associated with ischemia and reperfusion in the heart.
Russell
Raymond R
RR
Department of Internal Medicine (Section of Cardiovascular Medicine), Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA.
Li
Ji
J
Coven
David L
DL
Pypaert
Marc
M
Zechner
Christoph
C
Palmeri
Monica
M
Giordano
Frank J
FJ
Mu
James
J
Birnbaum
Morris J
MJ
Young
Lawrence H
LH
D055372:AMP-Activated Protein Kinases; D000818:Animals; D017209:Apoptosis; D005947:Glucose / Q000378:metabolism*; D006019:Glycolysis; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D017202:Myocardial Ischemia / Q000378:metabolism*; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000517:prevention & control*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*
D009097:Multienzyme Complexes; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases; D005947:Glucose