Intermittent exercise improves the vasoreactivity of the thoracic aorta in rats

Vasoreactivity is the most basic and direct indicator to reflect the artery vascular functional state in the body. The majority of previous studies have shown that a high-fat diet (HD) is often associated with a variety of cardiovascular diseases. However, the type of exercise that improves vasoreactivity, as is induced by a HD, remains to be elucidated. In the present study, the effects of aerobic moderate-intensity intermittent exercise through swimming were investigated on thoracic aorta vascular ring contraction and free radical metabolism using Sprague-Dawley rat models of common diet (CD; 23 g protein, 49 g carbohydrate, 4 g fat, 5 g fiber, 7 g bone meal and 6 g vitamins per 100 g), HD (peanuts, milk chocolate and sweet biscuits, in a weight ratio of 3:2:2:1), CD with intermittent exercise (CIE) and HD with intermittent exercise (HIE). The food utilization rate in the swimming group (CIE) decreased in comparison with the CD group. Lee's index in the CIE group decreased in comparison to that of CD after 8 weeks (P<0.05) and also HIE decreased compared to HD (P<0.05) after 8 weeks. Compared with the HD group, contractile response of the thoracic aortic rings to NA decreased in the HIE group, while high-density lipoprotein cholesterol content increased, total cholesterol, triglycerides and low-density lipoprotein cholesterol decreased (P<0.05); the malondialdehyde (MDA) concentration reduced in the myocardium, but the superoxide dismutase (SOD) level improved (P<0.05). In the HIE group, nitric oxide level was similar to the CD group. Compared with CD, contractile response of the thoracic aortic rings to NA increased in the CIE (P<0.05), the MDA concentration reduced in the myocardium, but the SOD level improved (P<0.05). Tunica media smooth muscle of the thoracic aortic rings in the CIE group arranged more regularly in comparison with the CD group (without swimming training). In conclusion, intermittent exercise improves the thoracic aorta vasoreactivity and function by enhanced antioxidant enzyme activity and reduced free radical generating.