title: Role of Rho kinase and oxidative stress in cardiac fibrosis induced by aldosterone and salt in angiotensin type 1a receptor knockout mice.
abstract: Large clinical trials have shown that mineralocorticoid receptor (MR) antagonists improve cardiovascular or total mortality in patients with heart failure or myocardial infarction even though the patients were taking angiotensin-converting enzyme inhibitors or angiotensin II receptor (AT1R) antagonists. We previously reported that cardiac fibrosis induced by aldosterone and salt (Ald-NaCl) was exaggerated in AT1aR knockout mice (AT1aR-KOs). As the association of Rho kinase and oxidative stress was reported in Ald-NaCl-induced hypertension of rats, we investigated the effects of an MR antagonist (eplerenone) and a Rho kinase inhibitor (fasudil) on Ald-NaCl-induced cardiac fibrosis in AT1aR-KOs. AT1aR-KOs were administered aldosterone (0.15 microg/h) subcutaneously using an osmotic minipump and were provided with 1% NaCl drinking water for 4weeks. AT1aR-KOs receiving Ald-NaCl were treated with a low (30 mg/kg/day) or high (100mg/kg/day) dose of eplerenone or a fasudil (100mg/kg/day). Systolic blood pressure (SBP), left ventricular weight/body weight (LVW/BW), histological examination and cardiac gene expression were evaluated on day 28. Ald-NaCl treatment caused increases in SBP and LVW/BW in AT1aR-KOs, and eplerenone dose-dependently decreased SBP, LVW/BW and cardiac fibrosis. Fasudil decreased LVW/BW and cardiac fibrosis without affecting SBP. The expressions of connecting tissue growth factor (CTGF) and nicotinamide adenine dinucleotide phosphate (NADPH) components (p22phox, p47phox and p67phox) were increased in Ald-NaCl-treated AT1aR-KOs, and eplerenone or fasudil decreased the expression of CTGF and NADPH components. Phosphorylated ERM (a marker of the phosphorylation of Rho kinase) was increased in Ald-NaCl-treated AT1aR-KOs and was decreased by eplerenone. Nitrotyrosine and 4-hydroxy-2-nonenal, which indicate tissue damage via oxidative stress, were increased in AT1aR-KO and were apparently attenuated by eplerenone or fasudil. These results suggested that the Rho kinase pathway was activated to induce cardiac fibrosis by Ald-NaCl via MR in AT1aR-KOs. A Rho kinase inhibitor as well as eplerenone might be useful for cardiac damage by Ald-NaCl.
authors.affiliation: Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan. kagishu@hotmail.com
authors.forename: Shuntaro
authors.initials: S
authors.lastname: Kagiyama
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Matsumura
authors.forename: Kenichi
authors.initials: K
authors.lastname: Goto
authors.forename: Toshio
authors.initials: T
authors.lastname: Otsubo
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Iida
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives / Q000494:pharmacology; D000450:Aldosterone; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D000077545:Eplerenone; D005355:Fibrosis / Q000139:chemically induced / Q000201:enzymology / Q000503:physiopathology; D006321:Heart / Q000187:drug effects*; D007150:Immunohistochemistry; D051379:Mice; D018345:Mice, Knockout; D000451:Mineralocorticoid Receptor Antagonists / Q000494:pharmacology; D009206:Myocardium / Q000201:enzymology / Q000473:pathology; D018384:Oxidative Stress; D044140:Receptor, Angiotensin, Type 1 / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012965:Sodium Chloride; D013148:Spironolactone / Q000031:analogs & derivatives / Q000494:pharmacology; D054460:rho-Associated Kinases / Q000378:metabolism*
chemical_list: D000451:Mineralocorticoid Receptor Antagonists; D044140:Receptor, Angiotensin, Type 1; D013148:Spironolactone; D012965:Sodium Chloride; D000450:Aldosterone; D000077545:Eplerenone; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D054460:rho-Associated Kinases; C049347:fasudil