Diabetes Care 30:1351-1356, 2007 DOI: 10.2337/dc06-1551 © 2007 by the American Diabetes Association
Impact of Telmisartan Versus Ramipril on Renal Endothelial Function in Patients With Hypertension and Type 2 Diabetes
1 Department of Nephrology and Hypertension, University of Erlangen-Nürnberg, Erlangen, Germany Address correspondence and reprint requests to R.E. Schmieder, Clinical Research Center Medizinische Klinik 4, Universitätsklinikum Erlangen, Krankenhausstrasse 12, 91054 Erlangen, Germany. E-mail: roland.schmieder{at}rzmail.uni-erlangen.de OBJECTIVEOne of the earliest signs of vascular change is endothelial dysfunction, which is also known to provoke albuminuria and to predict cardiovascular prognosis. The aim of this study was to analyze the effects of renin-angiotensin system (RAS) blockade on renal endothelial function. RESEARCH DESIGN AND METHODSIn a multicenter, prospective, double-blind, forced-titration, randomized study, 96 patients with type 2 diabetes, hypertension, glomerular filtration rate >80 ml/min, and normo- or microalbuminuria were treated once daily with 40/80 mg telmisartan or 5/10 mg ramipril for 9 weeks. RESULTSThe mean ± SE fall in renal plasma flow (RPF) in response to intravenous NG-monomethyl-L-arginine (L-NMMA), reflecting the magnitude of nitric oxide (NO) activity, increased with telmisartan from 71.9 ± 9.0 ml/min before therapy to 105.2 ± 9.7 ml/min at the end of treatment (P < 0.001). With ramipril, RPF response to L-NMMA increased from 60.1 ± 12.2 to 87.8 ± 9.2 ml/min (P = 0.018). The adjusted difference between treatments was 17.1 ± 13.7 ml/min (P = 0.214). In accordance, telmisartan increased RPF at rest (i.e., without L-NMMA) from 652.0 ± 27.0 to 696.1 ± 31.0 ml/min (P = 0.047), whereas ramipril produced no significant changes in RPF. The more the basal NO activity improved, the greater was the vasodilatory effect on renal vasculature (r = 0.47, P < 0.001). CONCLUSIONSIn patients with type 2 diabetes, telmisartan and ramipril both increased NO activity of the renal endothelium significantly, which in turn may support the preservation of cardiovascular and renal function.
Abbreviations: ARB, angiotensin II receptor blocker DBP, diastolic blood pressure GFR, glomerular filtration rate L-NMMA, NG-monomethyl-L-arginine MAP, mean arterial pressure RAS, renin-angiotensin system RPF, renal plasma flow SBP, systolic blood pressure
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