- 作者: Vilmante Borutaite; Ramune Morkuniene; Odeta Arandarcikaite; Aiste Jekabsone, Jurgita Barauskaite; Guy C Brown
- 作者服務機構: Institute for Biomedical Research, Kaunas University of Medicine, Kaunas, Lithuania
- 中文摘要: --
- 英文摘要:
Background :
Heart ischemia can rapidly induce apoptosis and mitochondrial dysfunction via
mitochondrial permeability transition-induced cytochrome c release. We tested whether
nitric oxide (NO) can block this damage in isolated rat heart, and, if so, by what
mechanisms.
Methods :
Hearts were perfused with 50 μM DETA/NO (NO donor), then subjected to 30 min stopflow
ischemia or ischemia/reperfusion. Isolated heart mitochondria were used to measure
the rate of mitochondrial oxygen consumption and membrane potential using oxygen and
tetraphenylphosphonium-selective electrodes. Mitochondrial and cytosolic cytochrome c
levels were measured spectrophotometrically and by ELISA. The calcium retention
capacity of isolated mitochondria was measured using the fluorescent dye Calcium
Green-5N. Apoptosis and necrosis were evaluated by measuring the activity of caspase-3
in cytosolic extracts and the activity of lactate dehydrogenase in perfusate, respectively.
Results :
30 min ischemia caused release of mitochondrial cytochrome c to the cytoplasm,
inhibition of the mitochondrial respiratory chain, and stimulation of mitochondrial proton
permeability. 3 min perfusion with 50 μM DETA/NO of hearts prior to ischemia
decreased this mitochondrial damage. The DETA/NO-induced blockage of
mitochondrial cytochrome c release was reversed by a protein kinase G (PKG) inhibitor
KT5823, or soluble guanylate cyclase inhibitor ODQ or protein kinase C inhibitors (Ro
32-0432 and Ro 31-8220). Ischemia also stimulated caspase-3-like activity, and this was
substantially reduced by pre-perfusion with DETA/NO. Reperfusion after 30 min of
ischemia caused no further caspase activation, but was accompanied by necrosis, which
was completely prevented by DETA/NO, and this protection was blocked by the PKG
inhibitor. Incubation of isolated heart mitochondria with activated PKG blocked
calcium-induced mitochondrial permeability transition and cytochrome c release.
Perfusion of non-ischemic heart with DETA/NO also made the subsequently isolated
mitochondria resistant to calcium-induced permeabilisation, and this protection was
blocked by the PKG inhibitor.
Conclusions :
The results indicate that NO rapidly protects the ischemic heart from apoptosis and
mitochondrial dysfunction via PKG-mediated blockage of mitochondrial permeability
transition and cytochrome c release. - 中文關鍵字: --
- 英文關鍵字: --