稳定性核素测定大鼠小肠蛋白质合成

目的：建立稳定性核素（[L-^15N]亮氨酸）测定大鼠小肠蛋白质合成率的方法。方法：分别测定静脉注射相同剂量[L-^15N]亮氨酸不同时相的大鼠小肠^15N丰度及不同剂量[L-^15N]亮氨酸同一时相的大鼠小肠^15N丰度。结果：大鼠小肠游离氨基酸池中^15N核素丰度在注射后0．5h内呈线性上升并达高峰，维持4h后缓慢下降，小肠蛋白质中的^15N丰度0．5h至12h基本维持不变；随着注射剂量的增加，大鼠小肠蛋白质分数合成率（FSR）亦增加，当[L-^15N]亮氨酸剂量在1．0mmol／kg以上，FSR并不随施加[L15N]亮氨酸剂量的加大而增加。结论：在进行大鼠小肠蛋白质合成率测定时，一次性静脉注射的测量最佳时限为0．5h，剂量为1．0mmol／kg。

Measurement of small intestine protein fractional synthesis rates with stable isotope

Objective: To develop a new technique for measuring synthesis rates of small intestinal protein in rats with [L-14N]Leucine. Methods: After intravenous injection of [L-14N]Leucine,the enrichment of ~(15)N in different time intervals with the same dosage and at fixed time by various dosage were measured. Results: During the period from 0 to 30 minutes,there is nearly a linear increase in enrichment of ~(15)N of free amino-acid pool to the peak in rats' small intestine.For bond amino-acid pool,the level of enrichment of ~(15)N is at its plateau between 0.5 and 12 hours with the increase of dosage,FSR did not rise with the increasing dosage of more than 1.0 mmol/kg of [L-14N]Leucine,there is no significant discrepancy. Conclusion: For measuring synthesis rate of small intestine protein in rats,30 minutes after mainlining is optimal and the most suitable dosage of [L-14N] Leucine is 1.0 mmol/kg.