Published online before print August 17, 2009, doi: 10.1161/HYPERTENSIONAHA.109.132886
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(Hypertension. 2009;54:738.)
© 2009 American Heart Association, Inc.
Original Articles |
Chronic Treatment With Losartan Results in Sufficient Serum Levels of the Metabolite EXP3179 for PPAR
Activation
From the Center for Cardiovascular Research (K.K., O.T., I.N.B., P.L.H., T.U., U.K.), Institute of Pharmacology, Charité-Universitätsmedizin Berlin, Germany; the Department of Medicine/Cardiology (J.K., J.F., P.S., E.F.), Deutsches Herzzentrum Berlin, Germany; the Institute of Pharmaceutical Chemistry/Technische Universität Braunschweig (I.O.), Braunschweig, Germany; and the Institute of Pharmacy (M.G., R.G.), Free University Berlin, Germany.
Correspondence to Ulrich Kintscher, MD, Center for Cardiovascular Research, Institute of Pharmacology, Charité-Universitätsmedizin Berlin, Hessische Str. 3-4, 10115 Berlin, Germany. E-mail ulrich.kintscher{at}charite.de
The losartan metabolite EXP3174 exhibits angiotensin II receptor 1 (AT1R)-blocking properties, whereas the metabolite EXP3179 potently induces the activity of the insulin-sensitizing peroxisome proliferator-activated receptor 
(PPAR) as a partial agonist in vitro. We investigated whether chronic treatment with losartan leads to sufficient serum levels of EXP3179 to activate PPAR in monocytes derived from losartan-treated patients. Hypertensive patients (n=15) treated with losartan (100 mg/daily for at least the past 2 months) and untreated control patients (n=7) were included. Monocytes were extracted by negative isolation using a Dynal Monocyte Kit, followed by analysis of PPAR target gene expression (CD36, ABC transporter G1 [ABCG1]) by quantitative real-time RT-PCR. Serum was prepared before, 2, 4, and 6 hours after losartan (100 mg) ingestion for HPLC-based determination of losartan, EXP3174, and EXP3179. Chronic treatment with losartan resulted in basal levels of losartan, EXP3174, and EXP3179 of 348.3±101.8 ng/mL, 115.3±56.1 ng/mL, and 176.2±143.4 ng/mL, respectively. Levels of both EXP3174 and EXP3179 were time-dependently increased in serum with a maximum 2 hours after drug intake (1706.0±760.1 ng/mL, 808.9±618.2 ng/mL, respectively). In consonance with detectable PPAR-activating EXP3179 serum levels, monocytic PPAR target gene expression was significantly upregulated in patients treated with losartan by 3.75±0.95- and 252.02±46.86-fold for CD36 and ABCG1 (P=0.043, P=0.0045 versus control patients, respectively). This is the first clinical description of monocytic PPAR-target gene regulation by chronic treatment with losartan, which likely is mediated by its metabolite EXP3179. Our data show that sufficient serum levels of EXP3179 are present under losartan treatment. PPAR activation by AT1R-blockers may translate into synergistic beneficial actions in monocytes.
Key Words: peroxisome proliferator-activated receptor gamma • angiotensin receptor blocker • losartan • CD36 • ABCG1 • monocytes • hypertension
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Hypertension 2009 54: 710-712.
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