Adrenomedullin inhibits angiotensin II-induced oxidative stress and gene expression in rat endothelial cells.
Adrenomedullin (AM), a potent vasodilator peptide, has recently been suggested to function as an endogenous antioxidant. However, its potential site of action at the cellular level has not been clarified. The present study was undertaken to investigate whether AM directly inhibits intracellular reactive oxygen species (ROS) generation and redox-sensitive gene expression stimulated by angiotensin (Ang) II in rat aortic endothelial cells (ECs). Ang II (10(-7) mol/l) significantly increased intracellular ROS levels in ECs as measured by dichlorofluorescein (DCF) fluorescence. AM inhibited Ang II-stimulated ROS generation in a dose-dependent manner and this effect was abolished by a superoxide radical scavenger, NAD(P)H oxidase inhibitor, and a protein kinase A (PKA) inhibitor, and mimicked by a cell-permeable cAMP analog. A real-time reverse transcription-polymerase chain reaction (RT-PCR) study showed that Ang II significantly upregulated a set of redox-sensitive genes (ICAM-1, VCAM-1, PAI-1, tissue factor, MCP-1, osteopontin), and these effects were blocked by an antioxidant, N-acetyl cysteine (NAC). AM similarly and dose-dependently inhibited the Ang II-induced upregulation of the entire set of these genes via a receptor-mediated and PKA-dependent pathway, and the degrees of inhibition were similar to those by NAC. In conclusion, the present study demonstrated that AM potently blocked the Ang II-stimulated intracellular ROS generation from NAD(P)H oxidase and the subsequent redox-sensitive gene expression via a cAMP-dependent mechanism in ECs, suggesting that AM has vasculoprotective effects against pro-oxidant stimuli.
Yoshimoto
Takanobu
T
Department of Clinical and Molecular Endocrinology, Tokyo Medical and Dental University Graduate School, Tokyo, Japan. tyoshimoto.cme@tmd.ac.jp
Gochou
Naoki
N
Fukai
Nozomi
N
Sugiyama
Toru
T
Shichiri
Masayoshi
M
Hirata
Yukio
Y
D000111:Acetylcysteine / Q000494:pharmacology; D053607:Adrenomedullin; D000804:Angiotensin II / Q000502:physiology*; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008297:Male; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors; D019255:NADPH Oxidases; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects*; D010455:Peptides / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation / Q000187:drug effects; D014665:Vasodilator Agents / Q000378:metabolism
D000975:Antioxidants; D004791:Enzyme Inhibitors; D010455:Peptides; D017382:Reactive Oxygen Species; D014665:Vasodilator Agents; D000804:Angiotensin II; D053607:Adrenomedullin; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; D017868:Cyclic AMP-Dependent Protein Kinases; D000111:Acetylcysteine