• Yoshiyu Takeda, Aoshuang Zhu, Takashi Yoneda, Mikiya Usukura, Hiroyuki Takata, and Masakazu Yamagishi.
• Division of Endocrinology and Hypertension, Department of Internal Medicine, Graduate School of Medical Science, Kanazawa University, Takara-machi, Kanazawa, Japan. takeday@im2.m.kanazawa-u.ac.jp
• Am. J. Hypertens. 2007 Oct 1; 20 (10): 1119-24.

BackgroundWe previously reported that a high-sodium diet activates the local renin-angiotensin-aldosterone system (RAAS) in cardiovascular tissues of Dahl salt-sensitive hypertensive (DS) rats. Angiotensin-converting enzyme 2 (ACE2) is a novel regulator of blood pressure (BP) and cardiac function. The effect of blockade of aldosterone or angiotensin II (Ang II) on cardiac angiotensinogen and ACE2 in DS rats is unknown.MethodsThe BP, plasma renin activity (PRA), plasma aldosterone concentration (PAC), heart weight, endothelium-dependent relaxation (EDR), and messenger RNA (mRNA) levels of collagen III, angiotensinogen, ACE, and ACE2 in the heart were measured in DS rats and in Dahl salt-resistant (DR) rats fed high or low salt diets. The rats were treated orally with or without eplerenone (100 mg/kg/d), candesartan (10 mg/kg/d), or both drugs combined for 8 weeks.ResultsA high salt diet increased BP (140%), heart/body weight (132%), and collagen III mRNA levels (146%) and decreased PRA and PAC concomitant with increased expression of cardiac angiotensinogen mRNA and decreased mRNA levels of ACE2 in DS rats. Eplerenone or candesartan significantly decreased the systolic BP from 240 +/- 5 mm Hg to 164 +/- 4 mm Hg or to 172 +/- 10 mm Hg, respectively (P < .05). Eplerenone or candesartan partially improved heart/body weight and cardiac fibrosis, improved EDR and decreased cardiac ACE and angiotensinogen mRNA levels in DS rats. Candesartan increased ACE2 mRNA levels in the heart. Combination therapy normalized BP and further improved cardiac hypertrophy, fibrosis, and EDR.ConclusionsIn DS rats, blockade of aldosterone or Ang II protects cardiac hypertrophy and fibrosis by inactivation of the local RAAS in the heart.

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