| Abstract: | Purpose: To explore the hypothesis that stent placement decreases dilator function of various arteries outside the stented segment and that angiotensin- (1-7) improves this function, and to assess the contribution of dilator signal compounds. A further objective was to test the hypothesis that on-stent delivery of Ang-(1-7) reduces neointima formation and improves endothelial function. Methods: Abdominal aortic stenting or sham operation was performed in the rat four weeks after stenting and treatment with intravenous saline or Ang-(1-7) infusion (24 µg/kg/h); vasomotor function in isolated thoracic aorta and brachial and iliac artery was measured in organ baths. Furthermore, Ang-(1-7)-eluting stents were designed and placed in rat abdominal aorta. Neointima formation and aortic function were tested after four weeks. Results: Relaxation of the thoracic aorta to metacholine was decreased after stenting compared with shams due to a decrease in nitric oxide-mediated response (67% reduction in maximal NO-dependent response). Ang-(1-7) restored the response mainly through increased prostaglandin- and possibly also endothelial-derived hyperpolarising factor-mediated relaxation. Relaxation in the brachial artery decreased after stenting (maximal response dropped by 50%), whilst contractions to phenylephrine increased. Ang-(1-7) normalised vasomotor function. Iliac artery function remained unaltered after stenting but Ang-(1-7) increased maximal relaxations by 65%. Delivery of Ang-(1-7) by means of a drug-eluting stent improved endothelial function. Conclusion: Stenting differentially affects dilator and contractile function in various arterial beds. Ang-(1-7) both improves dilator function and normalises contractile function. Delivery of protective peptides such as Ang-(1-7) from the stent is a new therapy option that merits further development and exploration. (Neth Heart J 2008;16:293-8.) |
