The rapid and reversible association of phosphofructokinase with myocardial membranes during myocardial ischemia

Myocardial calcium-independent phospholipase A₂ (PLA₂) activity is mediated by a 400 kDa catalytic complex comprised of a tetramer of phosphofructokinase (PFK) and a 40 kDa catalytic subunit [1,2]. During myocardial ischemia, calcium-independent PLA₂ activity rapidly and reversibly translocates from the cytosol to a membrane-associated compartment where it has been implicated as a mediator of ischemic damage [3,4]. Herein we demonstrate that the majority of both PFK mass and activity is translocated from the cytosol to a membrane-associated compartment prior to the onset of irreversible myocytic injury and that translocated PFK is catalytically inactive while membrane-associated. Furthermore, reperfusion of ischemic myocardium, or treatment of membranes derived from ischemic myocardium with ATP results in the conversion of both PFK mass and activity from its membrane-associated state to a soluble, catalytically-competent form. Collectively, these studies demonstrate that the concomitant changes in glycolysis and phospholipid hydrolysis during early myocardial ischemia result, at least in part, from the translocation of a common regulatory polypeptide critical in both processes.