title: Sublethal simulated ischemia promotes delayed resistance against ischemia via ATP-sensitive (K+) channels in murine myocytes: role of PKC and iNOS.
abstract: In this study, we examined whether sublethal simulated ischemia (SSI) induces delayed cellular protection in mouse cardiac myocytes, and whether the delayed cellular protection depends on the activation of protein kinase C-epsilon (PKC-epsilon), inducible nitric oxide synthase (iNOS), and ATP-sensitive K(+) (K(ATP)) channels against subsequent sustained simulated ischemia (SI). The following groups of mouse cardiac myocytes were studied: (a) SI: incubation with SI buffer for 1 h; (b) SSI: incubation with SSI buffer for 30 min; (c) SSI + PKC inhibitor, chelerythrine chloride (CCl): SSI and 1 micro M CCl; (d) SSI + iNOS inhibitor, S-methylthiourea (SMT): SSI and 100 nM SMT; (e) SSI + K(ATP) channel blocker, glibenclamide (Glb): SSI and 50 micro M Glb; (f) SSI + mitochondrial K(ATP) channel blocker, 5-hydroxydecanoate (5-HD): SSI and 50 micro M 5-HD. The release of lactate dehydrogenase into the medium and the amount remaining in the cells was measured, and A(1) adenosine receptor, PKC-epsilon, and iNOS were detected through western blot analysis. The delayed cellular protection acquired due to SSI showed a decreased release of lactate dehydrogenase (%) from 46.51 +/- 1.60 to 37.00 +/- 1.34 (p < 0.001) and was blocked by CCl (47.08 +/- 0.95), SMT (48.08 +/- 1.18), Glb (45.88 +/- 1.31), and 5-HD (47.20 +/- 1.56). Simultaneously, SSI-induced up-regulation of A(1) adenosine receptor, PKC-epsilon, iNOS, and opening of both membrane and mitochondrial K(ATP) channels also was observed compared with controls.
authors.affiliation: DIR ETP LPC MEM, National Institute of Environment and Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA. nayeem@niehs.nih.gov
authors.forename: Mohammed A
authors.initials: MA
authors.lastname: Nayeem
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D002478:Cells, Cultured; D003652:Decanoic Acids / Q000494:pharmacology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005905:Glyburide / Q000494:pharmacology; D006880:Hydroxy Acids / Q000494:pharmacology; D019194:Ischemic Preconditioning; D007550:Isothiuronium / Q000031:analogs & derivatives* / Q000494:pharmacology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D051379:Mice; D017202:Myocardial Ischemia / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D024661:Potassium Channels, Inwardly Rectifying / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D051744:Protein Kinase C-epsilon; D043682:Receptor, Adenosine A1 / Q000378:metabolism
chemical_list: D000889:Anti-Arrhythmia Agents; D003652:Decanoic Acids; D004791:Enzyme Inhibitors; D006880:Hydroxy Acids; D024661:Potassium Channels, Inwardly Rectifying; D043682:Receptor, Adenosine A1; D007550:Isothiuronium; C052853:5-hydroxydecanoic acid; D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; C497256:Prkce protein, mouse; D011493:Protein Kinase C; D051744:Protein Kinase C-epsilon; C027744:S-methylisothiopseudouronium; D005905:Glyburide