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Exercise training attenuates blood pressure elevation and adverse remodeling in the aorta of spontaneously hypertensive rats.

Horta PP, de Carvalho JJ, Mandarim-de-Lacerda CA

Laboratory of Morphometry and Cardiovascular Morphology, Biomedical Center, Institute of Biology, State University of Rio de Janeiro, Brazil.

OBJECTIVE: To observe the extracellular matrix modifications and quantify the structural alterations of the aortic wall in spontaneously hypertensive rats (SHR) submitted to an aerobic physical activity (PA) protocol. MATERIAL AND METHODS: Three groups of five rats each were studied: sedentary normotensive Wistar rats (SED-Wistar) and SHR (divided in SHR that underwent a 1 h/day 5 days/week PA for 20 weeks (EX-SHR) and those that were restricted to cage-bound activity (SED-SHR). RESULTS: BP was lower in EX-SHRs and SED-Wistar rats (-35%) than in SED-SHRs. This difference became significant from the 3rd week of PA. The wall thickness was smaller in the EX-SHR and SED-Wistar (-45%) than in the SED-SHR (p<0.0001). In EX-SHR group, oxytalan and elaunin fibers were more pronounced than in the other groups, while SED-SHR and SED-Wistar rats showed an equivalent appearance of aortic elaunin fibers. EX-SHR and SED-Wistar rats showed more than 65% greater smooth muscle nuclei numerical density per unit area than SED-SHRs while SED-SHRs showed more than 45% smaller surface density of lamellae than both EX-SHR and SED-Wistar rats. However, no quantitative differences were found in the aortic wall comparing EX-SHR and SED-Wistar rats. CONCLUSION: PA might alter the aortic wall remodeling to adapt the artery to a hyperkinetic blood flow resulting in alterations of the extracellular matrix modulation and vascular resistance.

Published 17 October 2005 in Life Sci, 77(26): 3336-43.
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