Objectives: We investigated the effects of treatment with the angiotensin II type 1 receptor antagonist, telmisartan, on abdominal aortic aneurysm formation in normotensive rats.
Methods: Abdominal aortic aneurysm was induced by perfusion of an isolated aortic segment with elastase. Treatment with telmisattan (0.5 mg/kg per day) or hydralazine (15 mg/kg per day) was started after surgery and continued for 14 days. Sham-operated animals and vehicle-treated animals after aneurysm induction served as controls. Aortic diameter was measured using ultrasound before aneurysm induction and on days 7 and 14 after aneurysm induction.
Results: On day 14, aortic diameter was increased two-fold in the vehicle-treated group compared to sham-operated animals (2.02 +/- 0.12 vs. 0.87 +/- 0.02 mm, P < 0.005, n = 8). Telmisartan treatment significantly reduced aneurysmal size (1.65 +/- 0.06 vs. 2.02 +/- 0.12 mm in vehicle, P < 0.05, n = 8), whereas treatment with hydralazine had no effect. Matrix metallopeptidase 3, cathepsin D, nuclear factor kappa B, tumour necrosis factor alpha, transforming growth factor-1 beta, as well as caspase 3, p53 and Fas ligand proteins, were significantly downregulated in aortic tissue under telmisartan compared to vehicle treatment. Serum monocyte chemoattractant protein 1 levels were also significantly decreased. Telmisartan and hydralazine reduced blood pressure to a similar extent within the observation period.
Conclusion: The angiotensin II type 1 receptor antagonist, telmisartan, prevents abdominal aortic aneurysm progression independently of blood pressure reduction by inhibiting proteolysis, apoptosis and inflammation in aortic tissue.