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目的通过饲喂大鼠赖氨酸(L-lysine,Lys)缺乏日粮,研究其对血清氨基酸(amino acid,AA)含量及对空肠和回肠上皮组织Lys及其它AA吸收的影响。方法体重240±20g的成年SD大鼠16只,随机分为2常规日粮(对照)和玉米醇溶蛋白日粮(Lys缺乏试验日粮)2组,试验期21d。实验末大鼠称重采血,断头处死,采集空肠和回肠样品,测定血清AA含量,尤斯灌流系统(Ussing Chamber)测定肠道转运AA变化及Lys的转运能力。结果试验组大鼠生长呈负增长,血清Lys、精氨酸(Arg)含量较对照组分别降低61.93%和33.08%(P<0.01),亮氨酸(Leu)和酪氨酸(Tyr)分别提高111.48%和63.43%(P<0.05),其他AA含量受Lys缺乏的影响不明显;试验组由扩散池经空肠或回肠向接收室的转运过程中Lys的消耗比率达到46.55%或51.28%,与对照组相比,分别显著增加了28.06%(P=0.006)或51.74%(P=0.001);在一定时间(60min)内,对照组和试验组Lys的转运经回肠吸收的累计透过量显著高于空肠(P<0.05),并伴随有其他AA的变化。结论日粮缺乏Lys导致大鼠生长性能降低,同时使空肠Lys通透率降低,而回肠Lys通透率提高。该结果为研究Lys等内源性AA的代谢机制提供了基础。
OBJECTIVE: To investigate the effect of dietary L-lysine (Lys) on the serum AA and Lys and other AA uptake in jejunum and ileal epithelium. Methods Sixteen adult Sprague-Dawley rats weighing 240 ± 20g were randomly divided into two groups: normal control (diet) and zein diet (Lys-deficient diet) for 21 days. At the end of the experiment, the rats were weighed, blood samples were collected and decapitated. The jejunum and ileum samples were collected for determination of serum AA content and Ussing Chamber for determination of intestinal transit AA and Lys transport capacity. Results The rats in the experimental group showed a negative growth, the contents of serum Lys and arginine were decreased by 61.93% and 33.08% (P <0.01), and Leu and Tyr 111.48% and 63.43% respectively (P <0.05). The contents of other AA were not significantly affected by Lys deficiency. The Lys consumption rate in the test group reached 46.55% or 51.28% during the transport from the diffusion cell through the jejunum or ileum to the receiving compartment. (P = 0.006) or 51.74% (P = 0.001), respectively. In a certain period of time (60min), the accumulated translocation of Lys transported by the ileum in the control group and the experimental group was significantly higher In jejunum (P <0.05), accompanied by changes in other AA. Conclusion The lack of dietary Lys led to a decrease in the growth performance of rats, while reducing the permeability of Lys in jejunum and increasing the permeability of Lys in Lys. This result provides a basis for studying the metabolic mechanism of endogenous AA such as Lys.