同位素^(65)Zn示踪法在研究膳食蛋白质与锌相互关系中的应用

THE APPLIANCE OF RADIOISOTOPE^(65)Zn TRACING METHOD IN THE STUDY OF THE INTERRELATIONSHIP BETWEEN DIETARY PROTEIN AND ZINC UTILIZATION IN RATS

本实验研究了不同来源膳食蛋白质及其摄取水平对大鼠锌吸收、分布、潴留、排泄及生物利用率的影响。结果表明：发芽大豆在各项指标上均优于普通大豆（Ｐ＜０．０１）；粪锌及粪￣（６５）Ｚｎ排出随膳食蛋白质水平的升高呈明显下降趋势，低蛋白组（５％）最高；表现￣（６５）Ｚｎ吸收率，表现Ｚｎ吸收率及表现Ｚｎ潴留率皆随膳食蛋白质水平增加而增加。５％蛋白质水平组明显低于蛋白质≥１０％各组（Ｐ＜０．０１），而１０％、１５％、２０％三组数值相接近，无显著性意义（Ｐ＞０．０５），提示低蛋白降低锌吸收与潴留，增加内源锌排泄；而１０％蛋白质，１５ｍｇ／ｋｇ锌为蛋白质和锌较适宜的膳食含量。在方法学上比较观察了￣（６５）Ｚｎ示踪法和总锌法。结果显示：大鼠肝、肾、胫骨、脑、睾丸各脏器Ｚｎ及￣（６５）Ｚｎ潴留存在明显正相关关系（Ｐ＜０．０５），且表现￣（６５）Ｚｎ吸收率与表现Ｚｎ吸收率、表现Ｚｎ潴留率呈高度正相关Ｐ（＜０．０５），示踪法特异性强，灵敏度高，无内源锌干扰，建议广泛使用，替代总锌法。

he effect of different dietary protein sources and levels on zinc intake,absorption,distribution,retention,excretion and bioavailibility in male we-anling Wistar rats were studied by ￣(65)Zn tracing method.The results showed that the germinated soybean had a greater advantage than that of common soybean in all indices (P<0.01).There was a significant(P<0.05) group was the highest.The apparent ￣(65)Zn absorbility,apparent Zn absorbility and apparent Zn retention(%)were significantly low(P<0.05)in groups fed by low protein(5%)as compared to those fed by≥10%protein diets(P<0.01);but there were no differences in 10%,15%,20%protein levels diet(P>0.05).The results not only indicated that a low protein diet reduced the absorption and retention of zinc and increased the excretion of endogenous zinc but also showed that the apparent Zn(￣(65)Zn)absorbility and the apparent Zn retention were maximum at l5mg/kg zinc and 10%protein level.It revealed that 10%protein and 15mg/kg zinc level might be desirable for maximum absorption and retention of zinc in rats. In the methodology,￣(65)Zn tracing method and total Zn met-hod were compared and discussed.There was a high correlation between tissue zinc and ￣(65)Zn retention of liver,kidney,tibia,brain,testis in rats(P<0.01)and among apparent ￣(65)Zn absorbility and apparent Zn absorbility,apparent Zn retention(%)(P<0.01).The isotope tracing method has hi-gher specificity and sensitivity and no endogenous zinc interference.It suggests that isotope ￣(65)Zn tracing method may be used widcly and substitute for the total zinc method.