Impact of Telmisartan Versus Ramipril on Renal Endothelial Function in Patients with Hypertension and Type 2 Diabetes

Abstract

Background: One of the earliest signs of vascular change is endothelial dysfunction, which is also known to provoke albuminuria and to predict cardiovascular prognosis. The study aimed to analyze the effects of renin-angiotensin-system (RAS) blockade on renal endothelial function.

Methods: In a multicenter, prospective, double-blind, forced-titration, randomized study, 96 patients with type 2 diabetes, hypertension, GFR >80 mL/min, and normo- or microalbuminuria were treated once daily with telmisartan 40/80 mg or ramipril 5/10 mg for 9 weeks.

Results: The (mean ± SE) fall in renal plasma flow (RPF) in response to intravenous N^G-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 end of treatment (p < 0.001). With ramipril, RPF response to L-NMMA increased from 60.1 ± 12.2 mL/min to 87.8 ± 9.2 mL/min (p = 0.018). The adjusted mean ± SE 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 mL/min 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).

Conclusions: In patients with type 2 diabetes telmisartan and ramipril both increased NO activity of the renal endothelium significantly that in turn may support the preservation of cardiovascular and renal function.