31 Pelletier, A. Joly, E. Prentki, M. Coderre, L. 2005 Endocrinology 146 5 2285-94 May 0013-7227 (Print) 15677757 p38 Mitogen-Activated Protein Kinases/*physiology Uncoupling Agents/pharmacology Transfection Signal Transduction Rats, Sprague-Dawley Rats inhibitors/genetics/*physiology Protein-Serine-Threonine Kinases/antagonists & Point Mutation Phosphorylation Myocytes, Cardiac/*drug effects/*metabolism Muscle Proteins/analysis Multienzyme Complexes/antagonists & inhibitors/genetics/*physiology Monosaccharide Transport Proteins/analysis Male Insulin/pharmacology Glucose Transporter Type 4 Glucose Transporter Type 1 Glucose/*metabolism Enzyme Inhibitors/pharmacology Enzyme Activation/drug effects Cells, Cultured Animals AMP-Activated Protein Kinases 2,4-Dinitrophenol/*pharmacology Sprague-Dawley Myocytes Cells Cultured Cardiac/*drug effects/*metabolism 2 4-Dinitrophenol/*pharmacology During metabolic stress, such as ischemia or hypoxia, glucose becomes the principal energy source for the heart. It has been shown that increased cardiac glucose uptake during metabolic stress has a protective effect on cell survival and heart function. Despite its physiological importance, only limited data are available on the molecular mechanisms regulating glucose uptake under these conditions. We used 2,4-dinitrophenol (DNP), an uncoupler of oxidative phosphorylation, as a model to mimic hypoxia and gain insight into the signaling pathway underlying metabolic stress-induced glucose uptake in primary cultures of rat adult cardiomyocytes. The results demonstrate that 0.1 mM DNP induces 2.2- and 9-fold increases in AMP-activated protein kinase (AMPK) and p38 MAPK phosphorylation, respectively. This is associated with a 2.3-fold increase in glucose uptake in these cells. To further delineate the role of AMPK in the regulation of glucose uptake, we used two complementary approaches: pharmacological inhibition of the enzyme with adenine 9-beta-D arabinofuranoside and adenoviral infection with a dominant-negative AMPK (DN-AMPK) mutant. Our results show that overexpression of DN-AMPK completely suppressed DNP-mediated phosphorylation of acetyl coenzyme A carboxylase, a downstream target of AMPK. Inhibition of AMPK with either 9-beta-D arabinofuranoside or DN-AMPK also abolished DNP-mediated p38 MAPK phosphorylation. Importantly, AMPK inhibition only partially decreased DNP-stimulated glucose uptake in cardiomyocytes. Inhibition of p38 MAPK with the pharmacological agent PD169316 also partially reduced (70%) glucose uptake in response to DNP. In conclusion, our results indicate that p38 MAPK acts downstream of AMPK in cardiomyocytes and that activation of the AMPK/p38 MAPK signaling cascade is essential for maximal stimulation of glucose uptake in response to DNP in adult cardiomyocytes. Journal ArticleResearch Support, Non-U.S. Gov'tUnited States http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=15677757