Structure, endothelial function, cell growth, and inflammation in blood vessels of angiotensin II-infused rats: role of peroxisome proliferator-activated receptor-gamma.

BACKGROUND: Pioglitazone and rosiglitazone, thiazolidinedione peroxisome proliferator-activated receptor-gamma (PPARgamma) activators, reduce blood pressure (BP) in some hypertensive models by unclear mechanisms. We tested the hypothesis that pioglitazone or rosiglitazone would prevent BP elevation and vascular dysfunction in angiotensin (Ang) II-infused rats by direct vascular effects. METHODS AND
RESULTS: Sprague-Dawley rats received Ang II (120 ng x kg(-1) x min(-1) SC) with or without pioglitazone (10 mg x kg(-1) x d(-1)) or rosiglitazone (5 mg x kg(-1) x d(-1)) for 7 days. Systolic BP, elevated in Ang II-infused rats (176+/-5 mm Hg) versus controls (109+/-2 mm Hg, P<0.01), was reduced by pioglitazone (134+/-2 mm Hg) or rosiglitazone (123+/-2 mm Hg). In mesenteric small arteries studied in a pressurized myograph, media/lumen ratio was increased (P<0.05) and acetylcholine-induced relaxation impaired in Ang II-infused rats (P<0.05); both were normalized by the thiazolidinediones. In Ang II-infused rats, vascular DNA synthesis (by 3H-thymidine incorporation); expression of cell cycle proteins cyclin D1 and cdk4, angiotensin II type 1 receptors, vascular cell adhesion molecule-1, and platelet and endothelial cell adhesion molecule; and nuclear factor-kappaB activity were increased. These changes were abrogated by pioglitazone or rosiglitazone.
CONCLUSIONS: Thiazolidinedione PPAR-gamma activators attenuated the development of hypertension, corrected structural abnormalities, normalized cell growth, and improved endothelial dysfunction induced by Ang II and prevented upregulation of angiotensin II type 1 receptors, cell cycle proteins, and proinflammatory mediators. Thiazolidinediones may be useful in the prevention and/or treatment of hypertension, particularly when it is associated with insulin resistance or diabetes mellitus.