Adenosine A1 receptor activation reduces opening of mitochondrial permeability transition pores in hypoxic cardiomyocytes.
1. Adenosine A(1) receptors (A(1)R) play an important role in cardioprotection against hypoxic damage and the opening of mitochondrial permeability transition pores (MPTP) is central to the regulation of cell apoptosis and necrosis. However, it is still unclear whether A(1)R open MPTP in hypoxic cardiomyocytes. 2. The present study used primary cardiomyocyte cultures from neonatal rats to investigate the mechanisms of A(1)R activation and the effects of A(1)R on MPTP opening under hypoxic conditions. 3. Hypoxia increased both MPTP opening and the production of reactive oxygen species (ROS), while decreasing cell viability and mitochondrial membrane potential (Deltapsi). The A(1)R agonist 2-chloro-N(6)-cyclopentyladenosine (CCPA; 500 nmol/L) blocked the increase in MPTP opening and ROS production and maintained cell viability and Deltapsi under hypoxic conditions. 4. The protective effects of CCPA were eliminated by both the protein kinase C (PKC) inhibitor chelerythine (2 micromol/L) and the mitochondrial ATP-sensitive K(+) channel (mitoK(ATP)) inhibitor 5-hydroxydecanoate (500 micromol/L). Moreover, CCPA significantly increased the PKC content in both total protein and membrane protein of cardiomyocytes. 5-Hydroxydecanoate did not prevent these CCPA-induced increases in PKC. 5. These results demonstrate that CCPA reduces MPTP opening in hypoxic cardiomyocytes, possibly by activating PKC, stabilizing Deltapsi and reducing ROS production following the opening of mitoK(ATP). Consequently, fewer MPTP open.
Institute of Burn Research, State Key Laboratory of Trauma, Burn and Combined Injury, Southwest Hospital, Third Military Medical University, Chongqing, China.
Fei
F
Xiang
Yue-sheng
YS
Huang
Dong-xia
DX
Zhang
Zhi-gang
ZG
Chu
Jia-ping
JP
Zhang
Qiong
Q
Zhang
D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D015687:Cell Hypoxia / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D000083162:Mitochondrial Permeability Transition Pore; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D043682:Receptor, Adenosine A1 / Q000378:metabolism* / Q000502:physiology
D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D043682:Receptor, Adenosine A1; C048599:N(6)-cyclopentyladenosine; D000241:Adenosine