Angiotensin II downregulates the fatty acid oxidation pathway in adult rat cardiomyocytes via release of tumour necrosis factor-alpha.
OBJECTIVE
Advanced heart failure is often associated with reduced myocardial fatty acid oxidation capacity. We have previously observed that failing hearts of mice with overexpression of angiotensinogen in the myocardium exhibit marked reduction of key regulatory proteins of fatty acid oxidation. In the present study, we determined whether exposure of adult rat cardiac (ARC) myocytes to angiotensin II (Ang II) influences expression of fatty acid translocase, muscle-type carnitine palmitoyl transferase-I, and medium-chain acyl-CoA dehydrogenase.


RESULTS
Ang II reduced mRNA expression of the three regulatory proteins in ARC myocytes during the entire 14-days culture period. However, protein expression and palmitate oxidation rate remained unaltered for 7 days, but subsequently markedly decreased. The decrease of protein expression and of fatty acid oxidation coincided with the onset of increased protein expression of tumour necrosis factor-alpha (TNF-alpha). The effect of Ang II was completely abolished by either blocking TNF-alpha formation through inhibition of reactive oxygen species-mediated activation of nuclear factor-kappaB or by neutralizing TNF-alpha with a specific antibody. Activation of peroxisome proliferator-activated receptor-alpha (PPARalpha) and PPARbeta/delta counteracted Ang II-mediated reduction of the fatty acid oxidation pathway.


CONCLUSIONS
Prolonged exposure of cardiac myocytes to Ang II elicits downregulation of the fatty acid oxidation pathway mediated by enhanced synthesis of TNF-alpha.
Pellieux
Corinne
C
Cardiology Center, Department of Medicine, University Hospitals of Geneva, Foundation for Medical Research, 64, avenue de la Roseraie, CH-1211 Geneva 4, Switzerland. corinne.pellieux@hcuge.ch
Montessuit
Christophe
C
Papageorgiou
Irène
I
Lerch
René
R
D042964:Acyl-CoA Dehydrogenase / Q000378:metabolism; D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D002334:Carnitine O-Palmitoyltransferase / Q000378:metabolism; D002478:Cells, Cultured; D005227:Fatty Acids / Q000378:metabolism*; D008297:Male; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D020097:Natriuretic Peptide, Brain / Q000378:metabolism; D010084:Oxidation-Reduction; D047493:PPAR alpha / Q000378:metabolism; D047494:PPAR delta / Q000378:metabolism; D047495:PPAR gamma / Q000378:metabolism; D048068:PPAR-beta / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D005227:Fatty Acids; D016328:NF-kappa B; D047493:PPAR alpha; D047494:PPAR delta; D047495:PPAR gamma; D048068:PPAR-beta; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; D000804:Angiotensin II; D020097:Natriuretic Peptide, Brain; D042964:Acyl-CoA Dehydrogenase; D002334:Carnitine O-Palmitoyltransferase