Remodeling of elastic layer of aortic artery after training by swimming in spontaneously hypertensive rats.

Hypertension is a major risk factor for cardiovascular diseases, in which the elastic properties of arteries are subjected to high pressure levels, and networks of elastic fibers may develop cleft longitudinal, transverse, breaks and fragmentation, and such structural changes (fibrosis and degradation of elastin) may lead to a decrease in the elasticity of the artery. The descending thoracic aortas of normotensive Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHRs) subjected to physical training through swimming or those of sedentary rats were prepared with hematoxylin-eosin and Verhoff to assess the artery medial. The images were captured with a videocamera coupled to an ordinary light microscope and the images were analyzed with the same program. SHRs showed a larger area of the medial layer of the thoracic aorta (F = 25,764, P < 0.001), and it was observed that rats submitted to physical training through swimming showed a larger area of the thoracic aorta (t = 3.206, P = 0.011). There was a higher percentage of elastic trained (F = 6.536, P = 0.019). To conclude, this study aimed to determine the elastic component of the aortic artery in animals that underwent exercise when compared with those that did not perform the activity, and analyze the relationship between the area of the aortic wall in trained and sedentary animals. The principal conclusion is that the rigidity of the aorta is not increased in SHRs subjected to physical training compared with that of trained WKY animals; however, when sedentary SHRs were analyzed there was a decrease in the elasticcomponent, which can characterize the aortic arterial stiffness in SHRs.