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Decreased mitochondrial oxidative phosphorylation capacity in the human heart with left ventricular systolic dysfunction
Author(s) -
Stride Nis,
Larsen Steen,
HeyMogensen Martin,
Sander Kåre,
Lund Jens T.,
Gustafsson Finn,
Køber Lars,
Dela Flemming
Publication year - 2013
Publication title -
european journal of heart failure
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.149
H-Index - 133
eISSN - 1879-0844
pISSN - 1388-9842
DOI - 10.1093/eurjhf/hfs172
Subject(s) - medicine , cardiology , oxidative phosphorylation , heart failure , human heart , mitochondrion , microbiology and biotechnology , biochemistry , biology
Aims Heart failure (HF) with left ventricular systolic dysfunction (LVSD) is associated with a shift in substrate utilization and a compromised energetic state. Whether these changes are connected with mitochondrial dysfunction is not known. We hypothesized that the cardiac phenotype in LVSD could be caused by reduced mitochondrial oxidative phosphorylation (OXPHOS) capacity and reduced mitochondrial creatine kinase (miCK) capacity. The study aim was to test mitochondrial OXPHOS capacity in LVSD myocardium compared with OXPHOS capacity in a comparable patient group without LVSD. Methods and results Myocardial biopsies were obtained from the left ventricle during cardiac valve or left ventricular assist device (LVAD) surgery. Patients were stratified according to left ventricular ejection fraction (LVEF) into LVSD (LVEF <45%, n = 14) or CONTROL (LVEF >45%, n = 15). Mitochondrial respiration was measured in muscle fibres with addition of non‐fatty acid substrates or octanoyl‐ l ‐carnitine, a medium chain fatty acid (MCFA). The in situ enzyme capacity of miCK was determined from APD titrations in the presence or absence of creatine. Maximal OXPHOS capacity with non‐fatty acid substrates was lower in the LVSD group compared with the CONTROL group ( P ≤ 0.05). ADP sensitivity always increased significantly ( P ≤ 0.05) with the addition of creatine, after which the sensitivity was highest ( P ≤ 0.05) in LVSD compared with CONTROL. The stimulation of OXPHOS from octanoyl‐ l ‐carnitine titrations elicited ∼40% lower respiration in LVSD compared with CONTROL ( P ≤ 0.05). Conclusion Human LVSD is associated with markedly diminished OXPHOS capacity, particularly in MCFA oxidation. This offers a candidate mechanism for a compromised energetic state and decreased reliance on fatty acid utilization in HF.