1995 Fiscal Year Final Research Report Summary
An approach to understand the pathophysiological role of endothelial constitutive nitric oxide synthase
| Project/Area Number |
06454292
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Circulatory organs internal medicine
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| Research Institution | Kobe University School of Medicine |
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Principal Investigator |
YOKOYAMA Mitsuhiro Kobe University School of Medicine The 1st Department of Internal Medicine Professor, 医学部, 教授 (40135794)
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| Co-Investigator(Kenkyū-buntansha) |
KAWASHIMA Seinosuke Kobe University School of Medicine The 1st Department of Internal Medicine Assos, 医学部・付属病院, 講師 (10177678)
KAWAHARA Yasuhiro Kobe University School of Medicine The 1st Department of Internal Medicine Assos, 医学部, 講師 (80169755)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Nitric oxide synthase / Oxidized low density lipoprotein / Lysophosphatidylcholine / Atherosclerosis / Vascular endothelial cells / Protein kinase C |
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| Research Abstract |
NO synthesized from L-arginine by the action of constitutive NO synthase (cNOS) in vascular endothelial cell plays an important role in the regulation of tissue perfusion. Endothelium-dependent relaxation (EDR) is markedly reduced in atherosclerotic arteries and the impairment of EDR is thought to be involved in the pathogenesis of ischemic heart disease. The purpose of the present study is to clarify the regulatory mechanisms of cNOS in vascular endothelial cells. Endothelial cNOS was phosphorylated by protein kinase C (PKC) and cAMP-dependent protein kinase. In cultured bovine aortic endothelial cells (BAECs) , phorbol esters such as TPA and PDBu inhibited NO release by A23187 as well as ATPgS through PKC activation. We employed RNase protection assay and immunoblotting to elucidate the effect of cytokine, mechanical stimuli and atherogenic lipoprotein on the expression of cNOS mRNA and protein levels in BAECs. Low concentration of ox-LDL (10mg protein/mL) or LPC (5mg/mL) upregulated cNOS mRNA levels. Furthermore, in situ hybridization and immunohistochemistry revealed that the cNOS mRNA and protein expression was normally observed in the endothelial cells overlying aortic fatty streaks in WHHL rabbits. These findings suggest that loss of EDRF activity associated with atherosclerosis is not due to an alteration of endothelial cNOS expression. In summary, ox-LDL and LPC in atherosclerotic lesion may cause endothelial dysfunction by the inhibition of receptor-mediated intracellular signaling pathway.
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