| Co-Investigator(Kenkyū-buntansha) |
UEYAMA Takashi Wakayama Prefecture Medicine University, 医学部, 講師 (50264875)
KIMURA Hiroko Juntendo University, School of Medicine, Lecturer, 医学部, 講師 (00053299)
UEMURA Koichi The University of Tokyo, Graduate School of Medicine, Reserch Associate, 大学院・医学系研究科, 助手 (30244586)
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| Research Abstract |
Heme-oxygenase (HO)-1, generates CO, thereby protecting the cells. We have shown that a Ca^<2+>-dependent protease calpain promotes necrotic death in the cardiogenic H9c2 cells under hypoxia through α-fodrin proteolysis. The Ca^<2+>-influx, α-fodrin proteolysis and schemic death, were inhibited by CO or L-type Ca^<2+>-channel inhibitor verapamil. Ischemia also induced mitochondrial depolarization, which was inhibited by CO or verapamil. HO-1 induction reduced the Ca^<2+>-influx and cell death after ischemia. Thus, exogenous and endogenous CO protect the cardiomyogenic cells against ischemia by inhibiting Ca^<2+>-influx through L-type Ca^<2+> channel and calpain activation.
After short (15, 30 min) and long (45, 60 min) time. of ischemia by coronary artery occlusion of the rats, reperfusion caused dilatation and constriction of arterioles, respectively. The vascular diameter was correlated with enhanced immunofluorescence for Akt and phosphorylated forms of serine 1177 residue 鋲NOS, and NO-bound form of guanylate cyclase (GC), as confirmed by western blotting. The constriction during reperfusion after 45 min of ischemia is related to the inhibition of Akt-mediated eNOS-Ser1177 phosphorylation, which was suppressed by a PKC inhibitor chelerythrine, a flavoprotein inhibitor DPI, or reactive oxygen species (ROS) scavengers MPG and Tiron. An endothelin receptor antagonist BQ123 alleviated the vasoconstriction by increasing NO availability but not eNOS phosphorylation. Thus, vascular patency correlated with eNOS-Ser1177 phosphorylation during ischemia-ieperfusion, and is affecled by ROS, PKC, and flavoproteins.
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