Submitted on April 15, 2008
Revised on April 10, 2009
Accepted on April 10, 2009
AMP-Activated Protein Kinase Influences Metabolic Remodeling in H9c2 Cells Hypertrophied by Arginine Vasopressin
Ramesh Saeedi1, Varun V. Saran1, Sherry S.Y. Wu1, Erika S. Kume1, Kim Paulson1, Annie P.K. Chan1, Hannah L Parsons2, Richard B Wambolt3, Jason R. B. Dyck4, Roger W Brownsey1, and Michael F. Allard1*
1 University of British Columbia
2 UBC
3 UBC / St Paul's Hospital
4 University of Alberta
* To whom correspondence should be addressed. E-mail: mallard{at}mrl.ubc.ca.
Substrate use switches from fatty acids toward glucose in pressure-overload induced cardiac hypertrophy with an acceleration of glycolysis being characteristic. The activation of AMP-activated protein kinase (AMPK) observed in hypertrophied hearts provides one potential mechanism for the acceleration of glycolysis. Here we have directly tested the hypothesis that AMPK causes acceleration of glycolysis in hypertrophied heart muscle cells. The H9c2 cell line, derived from embryonic rat heart, was treated with (1µM) arginine vasopressin (AVP) to induce a cellular model of hypertrophy. Rates of glycolysis and oxidation of glucose and palmitate were measured in non-hypertrophied and hypertrophied H9c2 cells and the effects of inhibiting AMPK determined. AMPK activity was inhibited by 6-[4-(2-Piperidin-1-yl-ethoxy)-phenyl)]-3-pyridin-4-yl-pyrrazolo [1,5-a]-pyrimidine (Compound C) or by adenovirus-mediated transfer of dominant negative AMPK (DN-AMPK). Compared to non-hypertrophied cells, glycolysis was accelerated and palmitate oxidation was reduced with no significant alteration in glucose oxidation in hypertrophied cells, a metabolic profile similar to that of in intact hypertrophied hearts. Inhibition of AMPK resulted in partial reduction of glycolysis in AVP-treated hypertrophied H9c2 cells. Acute exposure of H9c2 cells to AVP also activated AMPK and accelerated glycolysis. These elevated rates of glycolysis were not altered by AMPK inhibition, but were blocked by agents that interfere with calcium ion signaling, including extracellular EGTA, dantrolene and 2-aminoethoxydiphenyl borate. We conclude that the acceleration of glycolysis in AVP-treated hypertrophied heart muscle cells is partially dependent upon AMPK whereas the acute glycolytic effects of AVP are AMPK-independent and at least partially calcium-dependent.
