Makrecka 2013 Abstract MiP2013
|Makrecka-Kuka M, Volska K, Kuka J, Liepins E, Dambrova M (2013) The accumulation of long chain acyl-carnitines is a major cause of mitochondrial damage during ischemia. Mitochondr Physiol Network 18.08.|
Elevated fatty acid (FA) levels are associated with the increased risk for cardiovascular diseases. Although it has been shown that excessive exogenous FA cause mitochondrial dysfunction in isolated mitochondria and could play a detrimental role in myocardial ischemia-reperfusion injury. Our aim was to study the cardiac mitochondrial damage in relation to accumulation of FA derivatives during ischemia-reperfusion.
Male Wistar rats were used for the experiments. The effects of palmitoyl-coenzyme A and palmitoyl-carnitine on mitochondrial respiration were determined. The isolated rat heart ischemia-reperfusion experiment was performed based on Langendorff technique. Hearts were perfused with modified Krebs-Henseleit buffer solution containing 9,10-[3H]palmitate before or after left anterior descending coronary artery occlusion. Mitochondria were isolated from the non-risk area and the area at risk to measure radiolabeled FA. In addition, acyl-coenzyme A and acyl-carnitines (C2-C18) levels were determined in whole homogenate and mitochondrial fraction by UPLC MS/MS.
Both palmitoyl-coenzyme A and palmitoyl-carnitine inhibited mitochondrial OXPHOS capacity in a dose-dependent manner. The IC50 values for palmitoyl-coenzyme A and palmitoyl-carnitine were 4.7 ± 0.7 μM and 16 ± 2 μM, respectively.
After ischemia, cardiac 9,10-[3H]palmitate concentration was 3-fold higher in the area at risk compared to the non-risk area. After reperfusion, cardiac 9,10-[3H]palmitate concentration was decreased by 19%. Meanwhile, the 9,10-[3H]palmitate concentration was 3.4 times higher in mitochondria isolated from the area at risk. There was no difference in 9,10-[3H]palmitate concentration in mitochondria isolated after ischemia or after reperfusion. No accumulation of 9,10-[3H]palmitate in cardiac tissue and mitochondria were observed during reperfusion. These results indicate that FAs accumulate during ischemia, but not during reperfusion. Moreover, the accumulated FAs are not metabolized during reperfusion.
After ischemia, the cardiac concentrations of medium (C6-C12) and long chain (C14-C18) acyl-carnitines and long chain (C14-C18) acyl-coenzymes A in the area at risk were 17 ± 3 μM, 896 ± 140 μM and 10 ± 2 μM, respectively. The levels were increased 2-3 folds compared to the non-risk area. In cardiac mitochondria isolated from the area at risk only concentrations of long-chain acyl-carnitines and acyl-coenzyme A were significantly increased (144 ± 12 μM vs. 59 ± 12 μM and 29 ± 3 μM vs. 14 ± 2 μM). In cardiac tissue and mitochondria isolated from the area at risk, the concentration of palmitoyl-carnitine was 112 and 8 folds higher than concentration of palmitoyl-coenzyme A, respectively.
Our results demonstrate that long chain acyl-coenzymes A are more toxic to mitochondria than long chain acyl-carnitines. Nonetheless, due to higher concentrations of acyl-carnitines compared to acyl-coenzymes A, the accumulation of long chain acyl-carnitines is the major cause of cardiac mitochondrial damage.
Labels: Pathology: Cardiovascular Stress:Ischemia-reperfusion Organism: Rat Tissue;cell: Heart Preparation: Isolated mitochondria
Regulation: Fatty acid
1 - Latvian Institute of Organic Synthesis, Laboratory of Pharmaceutical Pharmacology, Riga, Latvia; 2 - Riga Stradins University, Faculty of Pharmacy, Riga, Latvia. - Email: firstname.lastname@example.org