Document Detail

An important role of increase in tetrahydrobiopterin via H2O2-JAK2 signalling pathway in late phase of ischaemic preconditioning.
MedLine Citation:
PMID:  20139166     Owner:  NLM     Status:  MEDLINE    
The goal of this study was to elucidate whether there is an increase in myocardial tetrahydrobiopterin (BH4), which is a cofactor for nitric oxide synthase, during the late phase of ischaemic preconditioning (IPC) leading to cardioprotection against myocardial infarction and, if so, to examine the induction mechanisms of BH4 synthesis. Rats were preconditioned with four cycles of 3 min left main coronary artery (LCA) occlusion followed by 10 min reperfusion. Twenty-four hours later, the rats were subjected to 20 min ischaemia by LCA ligation and 2 h reperfusion, and the infarct size was determined by 2,3,5-triphenyltetrazolium chloride staining. The IPC protocol reduced the infarct size, and increased the BH4 content and expression of GTP-cyclohydrolase I (GTPCH), which is the rate-limiting enzyme for BH4 synthesis. Administration of a GTPCH inhibitor attenuated both the reduction in infarct size and the increase in BH4 levels. Moreover, the increase in BH4 content was reduced by administration of catalase or a Janus tyrosine kinase-2 (JAK2) inhibitor. These observations suggest that upregulation of BH4 synthesis in the heart contributes to an acquisition of ischaemic tolerance in late IPC, and the increase in myocardial BH4 content seems to be mediated by the induction of GTPCH via the H(2)O(2)-JAK2 pathway.
Toshihito Hiroi; Teruaki Wajima; Yuji Kaneko; Yuji Kiuchi; Shunichi Shimizu
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Publication Detail:
Type:  Journal Article     Date:  2010-02-05
Journal Detail:
Title:  Experimental physiology     Volume:  95     ISSN:  1469-445X     ISO Abbreviation:  Exp. Physiol.     Publication Date:  2010 May 
Date Detail:
Created Date:  2010-04-21     Completed Date:  2010-07-12     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9002940     Medline TA:  Exp Physiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  609-21     Citation Subset:  IM    
Department of Pathophysiology, Showa University School of Pharmacy, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan.
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MeSH Terms
Biopterin / analogs & derivatives*,  biosynthesis
GTP Cyclohydrolase / antagonists & inhibitors,  metabolism*
Hydrogen Peroxide / metabolism*
Ischemic Preconditioning, Myocardial*
Janus Kinase 2 / antagonists & inhibitors,  metabolism*
Rats, Sprague-Dawley
Signal Transduction
Tumor Necrosis Factor-alpha / physiology
Tyrphostins / pharmacology
Reg. No./Substance:
0/Tumor Necrosis Factor-alpha; 0/Tyrphostins; 0/alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide; 17528-72-2/5,6,7,8-tetrahydrobiopterin; 22150-76-1/Biopterin; 7722-84-1/Hydrogen Peroxide; EC Kinase 2; EC Cyclohydrolase

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