Adenosine monophosphate - activated kinase (AMPK) plays a key role in the 
coordination of the heart's anabolic and catabolic pathways. It induces a 
cellular cascade at the center of maintaining energy homeostasis in the 
cardiomyocytes.. The activated AMPK is a heterotrimeric protein, separated into 
a catalytic α - subunit (63kDa), a regulating β - subunit (38kDa) and a γ - 
subunit (38kDa), which is allosterically adjusted by adenosine triphosphate 
(ATP) and adenosine monophosphate (AMP). The actual binding of AMP to the γ - 
subunit is the step which activates AMPK. AMPK serves also as a protein kinase 
in several metabolic pathways of the heart, including cellular energy sensoring 
or cardiovascular protection. The AMPK cascade represents a sensitive system, 
activated by cellular stresses that deplete ATP and acts as an indicator of 
intracellular ATP/AMP. In the context of cellular stressors (i.e. hypoxia, 
pressure overload, hypertrophy or ATP deficiency) the increasing levels of AMP 
promote allosteric activation and phosphorylation of AMPK. As the concentration 
of AMP begins to increase, ATP competitively inhibits further phosphorylation of 
AMPK. The increase of AMP may also be induced either from an iatrogenic emboli, 
percutaneous coronary intervention, or from atherosclerotic plaque rupture 
leading to an ischemia in the microcirculation. To modulate energy metabolism by 
phosphorylation and dephosphorylation is vital in terms of ATP usage, 
maintaining transmembrane transporters and preserving membrane potential. In 
this article, we review AMPK and its role as an important regulatory enzyme 
during periods of myocardial stress, regulating energy metabolism, protein 
synthesis and cardiovascular protection.