[Peripheral benzodiazepine receptor agonist Ro5-4864 inhibits mitochondrial permeability transition in rat heart].
Opening of mitochondrial permeability transition (MPT) pores leads to mitochondrial injury during oxidative stress. The peripheral benzodiazepine receptor (PBR) located at mitochondrial outer-membrane has been shown to be involved in several mitochondrial functions. In the present study, we used Ro5-4864, a PBR agonist, to test if activation of PBR could prevent MPT pore opening during Ca(2+) overloading. Cardiac mitochondria isolated from Sprague-Dawley rats were treated by 150 mmol/L Ca(2+) to induce MPT. Ro5-4864 (50, 100 and 200 micromol/L) was added into incubation buffer before adding 150 micromol/L Ca(2+). In additional group, atractyloside (ATR, 20 micromol/L), an opener of MPT pores was added 5 min before the addition of 100 micromol/L Ro5-4864. The change of absorbance at 520 nm was monitored with a spectrophotometer at 30 degrees C for 10 min. Western blot was used to detect cytochrome C loss. The mitochondrial membrane potential was monitored with the fluorescence dye JC-1. Ro5-4864 inhibited the decrease of absorbance at 520 nm compared to that in the untreated Ca(2+) group (P<0.01, P<0.05). In the presence of ATR, Ro5-4864 was not able to prevent MPT anymore. Opening of MPT pores by Ca(2+) decreased the content of cytochrome C in mitochondria, but increased cytochrome C content in cytosol. Ro5-4864 preserved cytochrome C content in mitochondria and led to less cytochrome C release to cytosol. ATR treatment reversed the protective effect of Ro5-4864 on cytochrome C content. Opening of MPT pores led to mitochondrial depolarization, whereas Ro5-4864 treatment maintained mitochondrial membrane potential. Thus, prevention of MPT by activation of PBR during calcium overloading maintains mitochondrial cytochrome C content and membrane potential. Activation of PBR during cardiac ischemia and reperfusion may be an alternative way for cardioprotection.
Li
Jing-Yuan
JY
Department of Anesthesiology, the First Affiliated Hospital, China Medical University, Shenyang 110001, China.
Wang
Jun-Ke
JK
Zeng
Yin-Ming
YM
D000818:Animals; D001278:Atractyloside / Q000494:pharmacology; D001570:Benzodiazepinones / Q000494:pharmacology*; D002352:Carrier Proteins / Q000819:agonists* / Q000378:metabolism / Q000502:physiology; D005260:Female; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000502:physiology / Q000528:radiation effects; D008929:Mitochondria, Heart / Q000502:physiology*; D033681:Mitochondrial Membrane Transport Proteins / Q000187:drug effects / Q000502:physiology*; D000083162:Mitochondrial Permeability Transition Pore; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000378:metabolism / Q000502:physiology
D001570:Benzodiazepinones; D002352:Carrier Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D011963:Receptors, GABA-A; C069997:Tspo protein, rat; D001278:Atractyloside; C028513:4'-chlorodiazepam