Jezek 2010 Physiol Res
| Ježek J, Jabůrek M, Zelenka J, Ježek P (2010) Mitochondrial phospholipase A2 activated by reactive oxygen species in heart mitochondria induces mild uncoupling. Physiol Res 59:737-47. |
Jezek J, Jaburek M, Zelenka J, Jezek P (2010) Physiol Res
Abstract: Homeostasis of reactive oxygen species (ROS) in cardiomyocytes is critical for elucidation of normal heart physiology and pathology. Mitochondrial phospholipases A2 (mt-PLA2) have been previously suggested to be activated by ROS. Therefore, we have attempted to elucidate physiological role of such activation. We have found that function of a specific i-isoform of mitochondrial phospholipase A2 (mt-iPLA2) is activated by tert-butylhydroperoxide in isolated rat heart mitochondria. Isoform specificity was judged from the inhibition by bromoenol lactone (BEL), a specific iPLA2 inhibitor. Concomitant uncoupling has been caused by free fatty acids, since it was inhibited by bovine serum albumin. The uncoupling was manifested as a respiration burst accompanied by a slight decrease in mitochondrial inner membrane potential. Since this uncoupling was sensitive to carboxyatractyloside and purine nucleotide di- and tri-phosphates, we conclude that it originated from the onset of fatty acid cycling mediated by the adenine nucleotide translocase (major contribution) and mitochondrial uncoupling protein(s) (minor contribution), respectively. Such a mild uncoupling may provide a feedback downregulation of oxidative stress, since it can further attenuate mitochondrial production of ROS. In conclusion, ROS-induced function of cardiac mt-iPLA2 may stand on a pro-survival side of ischemia-reperfusion injury. • Keywords: Heart mitochondrial phospholipase A2, Fatty acids, Uncoupling of mitochondria, Adenine nucleotide translocase, Defense against oxidative stress
• O2k-Network Lab: CZ Prague Jezek P
Labels:
Organism: Rat
Tissue;cell: Heart
Preparation: Isolated mitochondria
HRR: Oxygraph-2k
