The Effects Of Long Term Aerobic Exercise On The Hemorheology In Rats Fed With High-Fat Diet

Cardiovascular diseases (CVD) have become the leading cause of death in urban and rural areas in China. Hyperlipidemia plays an important role in the development of hypertension, coronary heart disease, diabetes, and stroke. It has become an important factor that threatens people’s health and the quality of life. Surveys show that there are160million people with hypertension and that the blood lipid in one third of adults is on the high side. Each year the patients with stroke induced by high blood pressure and high blood lipid reach almost1.5million. Therefore, to control blood lipid level and prevent the development of complications have become the main tasks in modern medicine. The wide use of blood lipid lowering drugs, especially statins, has achieved good therapeutic effects. But the long term and large dosage of medication not only increases the financial burden in patients but also induces such complications as liver dysfunction and Rhabdomyolysis, etc. Modern medicine thinks that, when the high blood lipid happens, the first step is to adjust diet and change life style to control its contributing factors. If the blood lipid is still high, medication can be administrated on this basis. Many researchers carried out a lot studies in the field of intervention of hyperlipidemia by exercising. It has been shown that exercise has preventive effects on hyperlipidemia and its complications in cardiovascular and cerebrovascular systems. WHO and other organizations advocate that exercising should be carried on in the patients with chronic metabolic diseases, such as hyperlipidemia.Objective:Hypercholesterolemia is one of the cardiovascular risk factors sensitive to prevention and interventions. In this study, a rat model with hyperlipidemia was created and subjected to long-term swimming training. The aim of present study is to investigate the effects and possible mechanism of long term aerobic exercise on the hemorheology in rats fed with high-fat diet.Methods:118male SD rats were randomly divided into three experimental groups of6rats each:control group, HF group and HF+E group. All rats were housed under the standard laboratory conditions (25±2℃, a12-hour light/dark cycle). Prior to experimental protocols, all rats were allowed to get acclimatized for1week. Control group received water and standard feeds for eight weeks. High-fat diet (HF) group was fed a cholesterol-enriched high-fat diet (4%cholesterol,10%lard,0.1%Cow Bile Salt) for eight weeks. And high-fat diet plus exercise (HF+E) group received cholesterol-enriched high-fat diet for8weeks and swam in water (35℃) for60min per day except rested two days every week.2Rats were weighed at the last day of each week after12hours of fasting.3Rat LW/BW, LEW/BW, serum TG, serum TC levels were measured. Hematoxylin&eosin (H&E) Staining and Oil Red O Staining were used to observe the level of hepatic steatosis.4Hemorheological properties, e.g., erythrocyte deformation index (DI), erythrocyte electrophoresis rate, erythrocyte osmotic fragility were measured.5Blood coagulation, including fibrinogen concentration(Fib), activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT) were measured.6Plasma malondialdehyde (MDA) was measured.Results:1We found that the rats fed with high-fat diet developed hypercholesterolmia and hepatic steatosis. The total cholesterol and triglyceride in the plasma were all impaired as compared to those of the rats fed with standard diet. But after exercise, the total cholesterol and triglyceride were significantly decreased (p＜0.05) and the severity of hepatic steatosis were reduced. For LW/BW, there were significant increases in both HF group and HF+E group (p＜0.05) as compared with control group. But meanwhile, it was much lower in HF+E group than that in HF group (p＜0.05). In terms of LEW/BW, there was a significant decrease in HF+E group as compared with control and HF group (p＜0.05). However, there was no statistic difference between control group and HF group.2. Long-term aerobic exercise improves the hemorheological properties in rat fed with high-fat diet. We measured DI among the groups and found that there was a significant decrease in HF group as compared with control group and HF+E group (p＜0.05). However, there was no statistic difference between control and HF+E group. A marked reduction was observed in the EM in HF group as compared with those in control and HF+E group (p＜0.05). The heamolysis rates (Hr) at145mOsm/kg were compared among groups. HF group had the highest Hr (p＜0.05compared to control), indicating the erythrocytes in this group are very fragile. No difference was observed between control and HF+E group, suggesting that aerobic exercise greatly lowered the fragility of erythrocytes.3Long-term aerobic exercise has moderate effects on the coagulative properties of blood in rats fed with high-fat diet. The plasma fibrinogen concentrations were markedly higher in HF and HF+E group than control (p＜0.05), but there was no statistic difference between HF group and HF+E group. APTT increased significantly in HF group, but it was reduced remarkably in HF+E group to a level even lower than control. PT in both HF and HF+E groups were lower than control while there was no difference between HF and HF+E groups. For TT, it had no statistic difference among the groups although HF+E group showed a downward trend.4Long-term aerobic exercise reduces the plasma lipid peroxidation in rats fed with high-fat diet. We found that HF group had much higher MDA concentration than control (p＜0.05), indicating the severe lipid peroxidation in rats fed with high-fat diet. In HF+E group, it was greatly reduced to a level colse to control, suggesting that aerobic exercise could correct the lipid peroxidation. Conclusions:1Long-term aerobic exercise reduces the hypercholesterolemia and the fat deposit in the livers of rats fed with high-fat diet. Long term aerobic exercise could improve lipid metabolism, reduce the oxidative stress.2Long-term aerobic exercise improve the hemorheological properties in animals on high fat diet or with hypercholesterolemia. The improved hemorheological properties would facilitate the microcirculation and oxygen supply.