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目的：研究大鼠全身辐射损伤后小肠吸收Ｌ－酪氨酸（Ｔｙｒ）的变化。方法：用在体门静脉取血法研究了６Ｇｙ６０Ｃｏγ线全身一次照射后不同时间以及不同剂量照射后第３ｄ大鼠小肠吸收Ｔｙｒ的变化，并测定相应的小肠上皮细胞计数、小肠粘膜钠－钾－ＡＴＰ酶（Ｎａ＋－Ｋ＋－ＡＴＰａｓｅ）活性以及Ｎａ＋的跨膜转运。结果：６Ｇｙγ线全身照射后第３ｄ出现小肠对Ｔｙｒ的吸收障碍，以后很快恢复，并持续在正常水平。随着照射剂量的加大，吸收障碍加重，但３Ｇｙ以下剂量照射，则不出现Ｔｙｒ的吸收障碍。小肠上皮细胞计数、Ｎａ＋－Ｋ＋－ＡＴＰａｓｅ活性和Ｎａ＋的跨膜转运的变化与小肠吸收Ｔｙｒ的变化基本一致。结论：辐射损伤后小肠对Ｔｙｒ的吸收障碍与小肠上皮细胞数量减少导致的吸收面积的下降以及Ｎａ＋－Ｋ＋－ＡＴＰａｓｅ活性下降导致的Ｎａ＋跨膜转运能力的减弱有关。
Objective: To study the change of L-tyrosine (Tyr) uptake in small intestine after radiation-induced systemic injury in rats. Methods: The changes of Tyr absorption in small intestine of rats exposed to 6Gy60Coγ ray at different time and different dose of irradiation were studied by the method of in vivo portal vein blood sampling. The corresponding intestinal epithelial cell count, sodium-potassium-ATP Enzyme (Na + -K + -ATPase) activity and transmembrane transport of Na +. RESULTS: Tyr absorption in the small intestine occurred on the 3rd day after 6Gyγ-ray irradiation and recovered rapidly thereafter, continuing to be normal. With the increase of irradiation dose, the absorption disorder is aggravated, but the radiation dose below 3Gy does not appear the absorption disorder of Tyr. Intestinal epithelial cell count, Na + -K + -ATPase activity and Na + transmembrane transport changes consistent with changes in intestinal absorption Tyr. Conclusion: Absorption barrier of Tyr in small intestine after radiation injury is related to the decrease of absorption area due to the reduction of intestinal epithelial cells and the decrease of Na + transmembrane transport ability caused by the decrease of Na + -K + -ATPase activity.