| Cardiovascular diseases have become the severe disease that threaten mankind health seriously. Coronary heart disease remains the most common cause of death in cardiovascular diseases and hypercholesterolemia is a major risk factor on the mortality and the incidence of coronary heart disease. Thus it is becoming a focus in medical research to search original natural product in lowing serum cholesterol concentration. Calcium is an essential nutrient and is required for critical biological functions. According to relevant research showed that high calcium intake has some functions of lowing serum cholesterol concentration and regulating serum lipid levels. The experiment investigated the effects of different doses of calcium intake on the concentration of serum lipids in experimental hypercholesterolemic rats.Healthy, 4-week old Wistar male rats of clean degree whose body weight were from 90g to 110g were adopted. After adapting feeding one week, the 10 rats were randomly divided into the control group according to the body weight,then the others were gaven new prepared high fat diet to develope the hypercholesterolemia model. After two weeks,all the rats fasted for 12h,then blood samples were taken from vein and tested serum lipid concentration. The serum chelosterol concentration of the hypercholesterolemic rats was observably higher than that of the control group statisticaly. Therefore the hypercholesterolemia model was developed successfully. According to the serum cholesterol concentration and the body weight,the rats were randomly divided into 3 groups with 10 rats each,including low dose group(0.5% calcium), mediate dose group(1.0% calcium) and high dose group(2.0% calcium).The rats in low, mediateand high dose group were fed experimental high fat diets contained different calcium concentration everyday. The rats in the control group were fed with normal diet.All animals were weighed each 7 days and feed intake were recorded every day. After continue for 42 days, all animals fasted for 12h, then blood sample were drawn from the vein of posterior orbit through medical canthus in all the rats. At the end of the experiment, all rats were anaesthesia with ether, sacrificed and dissect the body. The weight of liver, kidney, spleen and heart of the rays were weighed respectively and, the ratio of the organ and body weight was calculated. After soft tissue was removed, bilateral femora were harvested. The concentrations of serum TC, TG, HDL-C, and LDL-C were measured by using a biochemical autoanalyzer. Bone density was measured by drain. The experimental results( x±s)show as mean±standard deviation. ANOVA was carried out for comparison of the difference between groups means. LSD was performed for of the difference between the two groups means. Pair t-test was used for self-comparision.After 6w of calcium intake:(1) The weigh of rats in each test group and the control group was increased statistically compared with that at the initial(P<0.05 or P<0.01),but compared with the control group the body weight increases were not statistically obvious(P>0.05).The daily diet intake of rats in each group was similar(P>0.05);(2)Compared with the control group, the final value of serum cholesterol concentration in low dose group were decreased;Greater inhibition in elevation of serum cholesterol concentration was observed in the mediate dose group than in the control group;(3)Compared with the initial, the serum total triglyceride concentration in low,mediate and high dose group were decreased significantly(P<0.05 or P<0.01);(4)A significantly greater elevation of HDL cholesterol (P< 0.05) was observed in high dose group than in low dose group.(5)Greater inhibition in elevation of LDL cholesterol was observed in the low dose group and mediate dose group than in the control group;(6)Calcium supplementation in high dose group caused a significant decrease in the heart weight/body weight ratio index (P<0.05 or P<0.01) and increase in the kidneys weight/body weight ratio index(P<0.05 or P<0.01);(7)Bone density of rats in the low dose group was lower than the control group,but in the mediat and high dose group was higher.Adequate calcium intake decreases the level of serum cholesterol and glycerinate in hypercholesterolemic rats which were induced by high fat intake. Adequate calcium intake is helpful to relieve the symptom and the development of complications of hypercholesterolemia. Adequate calcium intake also inhibites elevation of serum LDL-C concentration,and at the same time prevent osteoporosis induced by hypercholesterolemia. No evident significance takes place in other blood lipids,although high calcium intake can make serum HDL-C concentration increase,also cause some fatal damages of heart and kidneys. Moreover calcium intake has no effect on feed intake and body weight gain of rats. A right range of calcium intake on lowing serum cholesterol concentration and improving blood lipid profiles and correlative mechanism need further study.
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