Markova 2017 MiPschool Obergurgl
Event: MiPschool Obergurgl 2017
Mammalian carbohydrate metabolism in the heart is a very complex process which depends on many factors. One of the key enzymes of energy homeostasis is the pyruvate dehydrogenase complex (PDH). This mitochondrial matrix multienzyme complex connects glycolysis and tricarboxylic acid cycle by catalyzing the oxidative decarboxylation of pyruvate into acetyl-CoA. Stimulation of PDH via inhibiton of its kinase (Figure 1) seems to be a promising intervention leading to mitochondrial respiration improvement and enhanced energy delivery in some serious cardiovascular diseases such as ischemic heart disease, diabetic cardiomyopathy and heart failure . The aim of our study was to characterize mitochondrial respiration in the left heart vetricle of Wistar rats after intraperitoneal administration of PDH kinase inhibitor – DCA (dichloroacetic acid) in vivo during normoxia and anoxia.
In our study, 11 rats were used. Five of them served as controls and 6 animals were injected with DCA in 2 doses, 60 and 15 minutes before decapitation (total DCA dose 1.5 mmol/kg intraperitoneally) . Rats were sacrificed, their hearts dissected and samples from left ventricles weighed (approximately 2 mg per chamber). Then the samples were homogenized by PBI-Shredder  (plastic lysis disc; 10/5 s) and mitochondrial respiration was evaluated by Oxygraph-2k (OROBOROS, Austria). A standardized SUIT protocol was used to characterize standard respiratory states (LEAK, OXPHOS and ROX); oxygen consumption was corrected for ROX and expressed per mg of tissue wet weight. Mitochondrial respiration was measured during normoxia (180 – 100 µM of O2) or after a period of anoxia (20 minutes; 0 µM of O2).
DCA application in vivo significantly increased not only Complex I-linked substrate OXPHOS states, but also OXPHOS I+II, OXPHOS II and Complex IV-linked oxygen consumption. A short period of anoxia did not significantly affect respiratory parameters in the control samples. In contrast, it slightly increased oxygen consumption in the state OXPHOS I+II in samples from rats after DCA administration.
Results of our study suggest that inhibition of PDH kinase by DCA leads to significant improvement in mitochondrial respiration in the rat left heart ventricles under normoxic conditions Interestingly, DCA also seems to increase mitochondrial respiration after short period of anoxia.
Labels: MiParea: Respiration
Stress:Oxidative stress;RONS Organism: Rat Tissue;cell: Heart Preparation: Homogenate
Coupling state: LEAK, OXPHOS Pathway: N, S, CIV, NS, ROX HRR: Oxygraph-2k Event: C1, Oral
- Marková M(1,2), Kancirova I(3), Tůma Z(2), Ferko M(3), Kuncová J(1,2)
- Dept Physiol;
- Biomedical Center, Fac Medicine Pilsen, Charles University, Czech Republic
- Inst Heart Research SAS, Bratislava, Slovakia. - [email protected]
Figure 1. Schematic view of pyruvate dehydrogenase (PDH) regulation. Inhibition of pyruvate dehydrogenase kinase by DCA (dichloroacetic acid) leads to stimulation of PDH.
- Sun W, Liu Q, Leng J, Zheng Y, and Li J (2015) The role of Pyruvate Dehydrogenase Complex in cardiovascular diseases. Life Sci 121:97–103.
- Josan S, Park JM, Hurd R, Yen YF, Pfefferbaum A, Spielman D, Mayer D (2013) In vivo investigation of cardiac metabolism in the rat using MRS of hyperpolarized [1- 13 C] and [2- 13 C]pyruvate,” NMR. Biomed 26:1680–7.
- Draxl A, Eigentler A, and Gnaiger E (2013) PBI-Shredder HRR- Set: preparation of tissue homogenates for diagnosis of mitochondrial respiratory function. Mitochondr Physiol Network 17.02:1-9.