Tissue-specific and substrate-specific mitochondrial bioenergetics in feline
cardiac and skeletal muscles |
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Authors: | Liselotte Bruun CHRISTIANSEN Flemming DELA J?rgen KOCH Takashi YOKOTA |
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Institution: | 1)Department of Veterinary Clinical and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlaegevej 16, DK-1870 Frederiksberg, Denmark;2)X-lab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen, Denmark |
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Abstract: | No studies have investigated the mitochondrial function in permeabilized muscle fiber
from cats. The aim of this study was to investigate tissue-specific and substrate-specific
characteristics of mitochondrial oxidative phosphorylation (OXPHOS) capacity in feline
permeabilized oxidative muscle fibers. Biopsies of left ventricular cardiac muscle and
soleus muscle, a type I-rich oxidative skeletal muscle, were obtained from 15 healthy
domestic cats. Enzymatic activity of citrate synthase (CS), a biomarker of mitochondrial
content, was measured. Mitochondrial OXPHOS capacity with various kinds of non-fatty-acid
substrates and fatty-acid substrate in permeabilized muscle fiber was measured by using
high-resolution respirometry. CS activity in the heart was 3 times higher than in the
soleus muscle. Mitochondrial state 3 respiration, ADP-stimulated respiration, with complex
I-linked and complex I+II-linked substrates, respectively, was significantly higher in the
heart than in the soleus muscle when normalized for muscle mass, but not for CS activity,
indicating that greater capacity for mitochondrial OXPHOS with these non-fatty-acid
substrates in the heart may depend on higher mitochondrial content. In contrast, the
soleus muscle had higher mitochondrial state 3 respiration with fatty acids than the heart
when normalized for CS activity, indicating greater capacity for fatty-acid oxidation per
mitochondrion in the soleus. Our findings suggest that there are tissue- specific and
substrate-specific quantitative and qualitative differences in mitochondrial OXPHOS
capacity between the different types of oxidative muscles from cats. |
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Keywords: | feline heart mitochondria oxidative phosphorylation skeletal muscle |
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