L-carnitine is essential to beta-oxidation of quarried fatty acid from mitochondrial membrane by PLA(2).
Mitochondrial beta-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 O(2) consumption without substrates, is caused by L-carnitine treatment. In this study, we investigated whether L-carnitine is essential to the beta-oxidation of quarried fatty acids from the mitochondrial membrane by phospholipase A(2) (PLA(2)) 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 PLA(2) 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 beta-oxidation of quarried fatty acids from the mitochondrial membrane by PLA(2).
Yano
Hiromi
H
Department of Health & Sports Science, Kawasaki University of Medical Welfare, Kurashiki, Okayama, Japan. yanohiro@mw.kawasaki-m.ac.jp
Oyanagi
Eri
E
Kato
Yasuko
Y
Samejima
Yoshiyuki
Y
Sasaki
Junzo
J
Utsumi
Kozo
K
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002331:Carnitine / Q000494:pharmacology*; D005227:Fatty Acids / Q000737:chemistry* / Q000378:metabolism; D008297:Male; D008930:Mitochondria, Liver / Q000187:drug effects* / Q000378:metabolism; D051336:Mitochondrial Membranes / Q000187:drug effects* / Q000378:metabolism; D009840:Oligomycins / Q000494:pharmacology; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects; D054467:Phospholipases A2 / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D014475:Uncoupling Agents / Q000494:pharmacology; D014803:Vitamin B Complex / Q000494:pharmacology*
D005227:Fatty Acids; D009840:Oligomycins; D014475:Uncoupling Agents; D014803:Vitamin B Complex; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D054467:Phospholipases A2; D002331:Carnitine