title: Preconditioning blocks cardiocyte apoptosis: role of K(ATP) channels and PKC-epsilon.
abstract: The aims of this study were to determine whether preconditioning blocks cardiocyte apoptosis and to determine the role of mitochondrial ATP-sensitive K(+) (K(ATP)) channels and the protein kinase C epsilon-isoform (PKC-epsilon) in this effect. Ventricular myocytes from 10-day-old chick embryos were used. In the control series, 10 h of simulated ischemia followed by 12 h of reoxygenation resulted in 42 +/- 3% apoptosis (n = 8). These results were consistent with DNA laddering and TdT-mediated dUTP nick-end labeling (TUNEL) assay. Preconditioning, elicited with three cycles of 1 min of ischemia separated by 5 min of reoxygenation before subjection to prolonged simulated ischemia, markedly attenuated the apoptotic process (28 +/- 4%, n = 8). The selective mitochondrial K(ATP) channel opener diazoxide (400 micromol/l), given before ischemia, mimicked preconditioning effects to prevent apoptosis (22 +/- 4%, n = 6). Pretreatment with 5-hydroxydecanoate (100 micromol/l), a selective mitochondrial K(ATP) channel blocker, abolished preconditioning (42 +/- 2%, n = 6). In addition, the effects of preconditioning and diazoxide were blocked with the specific PKC inhibitors Gö-6976 (0.1 micromol/l) or chelerythrine (4 micromol/l), given at simulated ischemia and reoxygenation. Furthermore, preconditioning and diazoxide selectively activated PKC-epsilon in the particulate fraction before simulated ischemia without effect on the total fraction, cytosolic fraction, and PKC delta-isoform. The specific PKC activator phorbol 12-myristate 13-acetate (0.2 micromol/l), added during simulated ischemia and reoxygenation, mimicked preconditioning to block apoptosis. Opening mitochondrial K(ATP) channels blocks cardiocyte apoptosis via activating PKC-epsilon in cultured ventricular myocytes. Through this signal transduction, preconditioning blocks apoptosis and preserves cardiac function in ischemia-reperfusion.
authors.affiliation: Department of Anesthesiology, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
authors.forename: Huiping
authors.initials: H
authors.lastname: Liu
authors.forename: Hong Yan
authors.initials: HY
authors.lastname: Zhang
authors.forename: Xiangdong
authors.initials: X
authors.lastname: Zhu
authors.forename: Zuohui
authors.initials: Z
authors.lastname: Shao
authors.forename: Zhenhai
authors.initials: Z
authors.lastname: Yao
mesh_terms: D000470:Alkaloids; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D053119:Benzophenanthridines; D002478:Cells, Cultured; D002642:Chick Embryo; D003652:Decanoic Acids / Q000494:pharmacology; D003981:Diazoxide / Q000494:pharmacology; D006321:Heart / Q000187:drug effects / Q000196:embryology / Q000502:physiology*; D006880:Hydroxy Acids / Q000494:pharmacology; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D007473:Ion Channels / Q000502:physiology; D019157:Ischemic Preconditioning, Myocardial; D007527:Isoenzymes / Q000378:metabolism*; D008565:Membrane Proteins / Q000187:drug effects / Q000502:physiology*; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000166:cytology*; D010617:Phenanthridines / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology; D011493:Protein Kinase C / Q000378:metabolism*; D051744:Protein Kinase C-epsilon; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D000470:Alkaloids; D053119:Benzophenanthridines; D003652:Decanoic Acids; D006880:Hydroxy Acids; D007473:Ion Channels; D007527:Isoenzymes; D008565:Membrane Proteins; D010617:Phenanthridines; D015221:Potassium Channels; C117780:mitochondrial K(ATP) channel; C052853:5-hydroxydecanoic acid; C016299:chelerythrine; D011493:Protein Kinase C; D051744:Protein Kinase C-epsilon; D013755:Tetradecanoylphorbol Acetate; D003981:Diazoxide