The Effects Of Chronic Swimming Training On Aortic Structure, Endothelin-1 And Endothelin-1 Receptor In Aging Rats

Aging contributes to the injury and dysfunction of vascular endothelia cell, thus the balance between vasoconstrictors and vasodilators destroyed. Endothelin-1 is thought to contribute to the pathology of some cardiovascular diseases. Exercise training can affect endothelia morphology and endothelin-1 secretion by changing the demodynamic parameters, which is thought to the mechanism of prevention from and therapy of cardiovascular diseases.Purpose: Presently very seldom researches focus on the effects of chronic swimming training on endothelin-1 and the endothelin-1 Receptor in aging rats. The purpose of this paper is to investigate the effects of different chronic swimming training on aortic structure, endothelin-1 and endothelin-1 Receptor in Aging Rats.Subjects: In this paper, the 2 and 9-10 months old rats were divided into sedentary control groups and 14-week swimming training groups respectively. Swimming training rats were divided into one-hour swimming training per day (6 days/week), two-hour swimming training per day (6 days/week), and one-hour swimming training per day (3 days/week). After swimming training, the age of rats increased as 6 and 13-14 months respectively.Methods: ET-1 protein in thoracic aorta, renal tissue and plasma was determined by radioimmunoassay. The concentration of ETA-R in renal tissue was measured by ELISA. The level of SOD, MDA, NO and T-AOC were determined by reagent detection kits from Nanjing Institute of Biology Research. Aortic specimens were made for transmission electron microscope. Body weights were measured.Results: (1) As aging, the body weight increased (P<0.01) in 2-month old rats and it significantly lowered in swimming training rats compared with sedentary control group (P<0.01). The body weight increased as aging (P<0.05) in 9-10 months old sedentary rats, but keep steady in swimming training rats. (2) The endothelium of aorta shrunk and denatured, and there were some red blood cells adhered to the surface of endothelium in 13-14 months old sedentary rats. There were lots of collagenous fibers in the medium of endothelium. The structure of the aortic endothelium was integrity except there was some hairiness in 6 months old sedentary rats. Compared to 13-14 months old rats, there were not any red blood cells adhered to the surface of endothelium in 6months old sedentary rats. But there were lots of collagenous fibers in the medium. Also, there were some fat drops in fibrocyte. The structure of VEC was integrity, the elastic fibers of the inner-layer distributed equably and there were fewer collagenous fibers in the swimming training groups. (3) Compared with control groups, the concentration of the plasma ET-1 increased lightly but no significant difference in swimming training groups, except the difference in E2Y was significant (P<0.01). (4) As the increase of age, the concentration of ET-1 in thoracic aorta and renal tissues increased significantly (P<0.01). Compared to control groups, the concentration of ET-1 in thoracic aorta and renal tissues did not change significantly in 6-month swimming training rats, but reduced significantly in 13-14 months rats (P<0.01). (5) As the increase of age, the concentration of ETA-R in renal tissues reduced significantly. But swimming training did not affect the concentration of ETA-R in renal tissues. (6) The balance between oxidation and anti-oxidation was not destroyed in 13-14 months rats. (7) As the increase of age, the concentration of Nitric Oxide (NO) did not change significantly, but it increased significantly (P<0.05) in 13-14 months swimming training rats.Conclusions: (1) Swimming training can reduce or maintain the body weight of rats. The longer duration and the higher the frequency was, the more the body weight lost. (2) The endothelium was injured obviously in 13-14 months sedentary rats. There were lots of collagenous fibers in the inner-layer of endothelium in 2-month old sedentary rats, which means the trend to aging. Feasible swimming training helped to maintain the structure of endo...