The stimulation of heart glycolysis by increased workload
does not require AMP-activated protein kinase but a wortmannin-sensitive
Beauloye C, Marsin AS, Bertrand L, Vanoverschelde JL, Rider MH, Hue L.
Hormone and Metabolic Research Unit, Christian de Duve Institute of Cellular
Pathology, ICP-UCL 7529, 75, avenue Hippocrate, Brussels, Belgium.
Increasing heart workload stimulates glycolysis by enhancing glucose transport
and fructose-2,6-bisphosphate (Fru-2,6-P(2)), the latter resulting from
6-phosphofructo-2-kinase (PFK-2) activation. Here, we investigated whether
adenosine monophosphate (AMP)-activated protein kinase (AMPK) mediates PFK-2
activation in hearts submitted to increased workload. When heart work was
increased, PFK-2 activity, Fru-2,6-P(2) content and glycolysis increased,
whereas the AMP:adenosine triphosphate (ATP) and phosphocreatine/creatine (PCr:Cr)
ratios, and AMPK activity remained unchanged. Wortmannin, the well-known
phosphatidylinositol-3-kinase inhibitor, blocked the activation of protein
kinase B and the increase in glycolysis and Fru-2,6-P(2) content induced by
increased work. Therefore, the control of heart glycolysis by contraction
differs from that in skeletal muscle where AMPK is involved.