Abstract
Mitochondrial β-oxidation is an important system involved in the energy production of various cells. In this system, the function of l-carnitine is essential for the uptake of fatty acids to mitochondria. However, it is unclear whether or not endogenous respiration, ADP-induced O2 consumption without substrates, is caused by l-carnitine treatment. In this study, we investigated whether l-carnitine is essential to the β-oxidation of quarried fatty acids from the mitochondrial membrane by phospholipase A2 (PLA2) using isolated mitochondria from the liver of rats. Intact mitochondria were incubated in a medium containing Pi, CoA and l-carnitine. The effect of l-carnitine treatment on ADP-induced mitochondrial respiration was observed without exogenous respiratory substrate. Increase in mitochondrial respiration was induced by treatment with l-carnitine in a concentration-dependent manner. Treatment with rotenone, a complex I blocker, completely inhibited ADP-induced oxygen consumption even in the presence of l-carnitine. Moreover, the l-carnitine dependent ADP-induced mitochondrial oxygen consumption did not increase when PLA2 inhibitors were treated before ADP treatment. The l-carnitine-dependent ADP-induced oxygen consumption did contribute to ATP productions but not heat generation via an uncoupling system. These results suggest that l-carnitine might be essential to the β-oxidation of quarried fatty acids from the mitochondrial membrane by PLA2.
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Abbreviations
- CPT-I:
-
Carnitine palmitoyl transferase I
- OCTN2:
-
Organic cation/carnitine transporter 2
- PLA2 :
-
Phospholipase A2
- CoA:
-
Coenzyme A
- HPG:
-
4-Hydroxy-l-phenylglycine
- BPB:
-
Bromophenacylbromide
- MFA:
-
Mefenamic acid
- AA:
-
Aristolochic acid
- EGTA:
-
Ethylene glycol tetraacetic acid
- RCR:
-
Ratio of respiratory control
- BSA:
-
Bovine serum albumin
- iPLA2 :
-
Ca2+-independent PLA2
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Acknowledgements
This study was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science, Sports and Culture of Japan (C-#2100700).
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Yano, H., Oyanagi, E., Kato, Y. et al. l-Carnitine is essential to β-oxidation of quarried fatty acid from mitochondrial membrane by PLA2. Mol Cell Biochem 342, 95–100 (2010). https://doi.org/10.1007/s11010-010-0472-z
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DOI: https://doi.org/10.1007/s11010-010-0472-z