Nicorandil inhibits oxidative stress-induced apoptosis in cardiac myocytes through activation of mitochondrial ATP-sensitive potassium channels and a nitrate-like effect.
The anti-anginal drug nicorandil has been shown to inhibit apoptosis by activating mitochondrial ATP-sensitive potassium (K(ATP)) channels. The possible contribution of the nitrate moiety of this drug to its anti-apoptotic effect has now been investigated in neonatal rat ventricular myocytes subjected to oxidative stress. Exposure of cultured myocytes to 100 micromol/l hydrogen peroxide (H(2)O(2)) increased the number of nuclei stained by the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling technique as well as induced internucleosomal DNA fragmentation, loss of mitochondrial membrane potential, cytochrome c release into the cytosol, and activation of caspases-3 and -9, all of which are characteristics of apoptosis. Pretreatment of cells with nicorandil (100 micromol/l) inhibited these effects of H(2)O(2). Both the mitochondrial K(ATP) channel antagonist 5-hydroxydecanoate (5-HD) and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), an inhibitor of soluble guanylyl cyclase, attenuated the anti-apoptotic effect of nicorandil in concentration-dependent manners. Coapplication of ODQ (10 micromol/l) and 5-HD (500 micromol/l) completely abolished nicorandil-induced cytoprotection. The effect of nicorandil was also reduced by an inhibitor of cGMP-dependent protein kinase (KT5823, 1 micromol/l). The nitric oxide donor (+/-)-S-nitroso-N-acetylpenicillamine (SNAP, 50 micromol/l) mimicked the protective effect of nicorandil in a manner sensitive to ODQ but not to 5-HD. A cell-permeable cGMP analog, 8-bromo-cGMP, also reduced H(2)O(2)-induced apoptosis. The inhibition of the H(2)O(2)-induced activation of caspase-3, but not that of caspase-9, by nicorandil in the presence of 5-HD or by SNAP was reversed by the addition of dithiothreitol to the enzyme assay. Nicorandil inhibits oxidative stress-induced apoptosis in cardiac myocytes through a nitric oxide/cGMP-dependent mechanism as well as by activating mitochondrial K(ATP) channels.
Nagata
Kohzo
K
Department of Cardiology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan. nagata@med.nagoya-u.ac.jp
Obata
Koji
K
Odashima
Mari
M
Yamada
Akira
A
Somura
Fuji
F
Nishizawa
Takao
T
Ichihara
Sahoko
S
Izawa
Hideo
H
Iwase
Mitsunori
M
Hayakawa
Akemi
A
Murohara
Toyoaki
T
Yokota
Mitsuhiro
M
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects*; D002227:Carbazoles / Q000494:pharmacology; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D017869:Cyclic GMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D003600:Cytosol / Q000378:metabolism; D006352:Heart Ventricles / Q000166:cytology; D007211:Indoles / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009206:Myocardium / Q000166:cytology; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D020108:Nicorandil / Q000494:pharmacology*; D009566:Nitrates / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D015221:Potassium Channels / Q000819:agonists*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013347:Subcellular Fractions
D002227:Carbazoles; D007211:Indoles; D009566:Nitrates; D015221:Potassium Channels; C073601:KT 5823; D020108:Nicorandil; D000255:Adenosine Triphosphate; D017869:Cyclic GMP-Dependent Protein Kinases; D020169:Caspases