Objective: To study the relationship between Ca 2+ intake,Ca 2+ absorption and Ca 2+ retention. Methods; Thirty-six weaning rats were firstly fed with Ca-poor diet for a 3-week Ca 2+ depletion period,and ...Objective: To study the relationship between Ca 2+ intake,Ca 2+ absorption and Ca 2+ retention. Methods; Thirty-six weaning rats were firstly fed with Ca-poor diet for a 3-week Ca 2+ depletion period,and then randomly divided into 3 groups to receive diet with low,adequate and high Ca 2+ contents.The experiment lasted 12 weeks,with a 3-day metabolism experiment conducted in the 5th week. Results:Supplement with adequate amount of Ca 2+ increased bone Ca 2+,bone mineral density(BMD),bone mineral content(BMC)and the weight of femur(P<0.05).Higher doses of Ca 2+ failed to further improve the efficiency.Analysis showed that Ca 2+ intake was positively correlated to bone Ca 2+,BND and BMC,and negatively correlated to the rates of Ca 2+ absorption and retention.Dose-effect study revealed that the Ca 2+ absorption rate()was a hyperbola function of Ca 2+ intake(X),i.e.=e 6.8068×X -0.8821+20(F=47.3154,P<0.0001).It was found from the results that bone Ca 2+ content(determined by atom absorption spectrophotometer)had a linear correlation to BMC(determined with uni-photon bone mineral densitometer). Conclusion:The rate of Ca 2+ absorption is a hyperbola function of Ca 2+ intake.The increment of Ca 2+ absorption will be minimal when Ca 2+ intake exceeds 3d 250 mg in rats.BMC,better than BMD,may substitute for the ideal bone Ca 2+ content as the index to assess the efficacy of Ca 2+ supplement.展开更多
文摘Objective: To study the relationship between Ca 2+ intake,Ca 2+ absorption and Ca 2+ retention. Methods; Thirty-six weaning rats were firstly fed with Ca-poor diet for a 3-week Ca 2+ depletion period,and then randomly divided into 3 groups to receive diet with low,adequate and high Ca 2+ contents.The experiment lasted 12 weeks,with a 3-day metabolism experiment conducted in the 5th week. Results:Supplement with adequate amount of Ca 2+ increased bone Ca 2+,bone mineral density(BMD),bone mineral content(BMC)and the weight of femur(P<0.05).Higher doses of Ca 2+ failed to further improve the efficiency.Analysis showed that Ca 2+ intake was positively correlated to bone Ca 2+,BND and BMC,and negatively correlated to the rates of Ca 2+ absorption and retention.Dose-effect study revealed that the Ca 2+ absorption rate()was a hyperbola function of Ca 2+ intake(X),i.e.=e 6.8068×X -0.8821+20(F=47.3154,P<0.0001).It was found from the results that bone Ca 2+ content(determined by atom absorption spectrophotometer)had a linear correlation to BMC(determined with uni-photon bone mineral densitometer). Conclusion:The rate of Ca 2+ absorption is a hyperbola function of Ca 2+ intake.The increment of Ca 2+ absorption will be minimal when Ca 2+ intake exceeds 3d 250 mg in rats.BMC,better than BMD,may substitute for the ideal bone Ca 2+ content as the index to assess the efficacy of Ca 2+ supplement.
