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目的研究荆芥内酯在大鼠小肠中的吸收动力学特征。方法建立大鼠在体肠循环模型,采用酚红标记法校正循环液体积,HPLC测定不同时刻循环液中荆芥内酯的含量。结果不同质量浓度(1.84、3.68、7.36μg.mL-1)荆芥内酯的吸收速率常数Ka分别为(0.202 8±0.007 0)、(0.158 9±0.011 4)、(0.134 2±0.012 2)h-1,且各组之间均有显著性差异(P<0.05);质量浓度为3.68μg.mL-1的荆芥内酯在大鼠十二指肠、空肠、回肠的吸收速率常数Ka分别为(0.023 8±0.000 6)、(0.012 5±0.000 5)、(0.016 5±0.000 8)h-1,各组之间均有显著性差异(P<0.05)。结扎胆管与否以及肠道菌群的破坏,对荆芥内酯的肠吸收影响不大。加入P-gp抑制剂组与对照组比较,其Ka值之间存在显著性差异(P<0.05)。结论荆芥内酯在大鼠肠道的吸收呈一级动力学过程,吸收机制为主动转运;在大鼠各肠段均有吸收,其中十二指肠为其最佳吸收部位。
Objective To study the absorption kinetics of nepetalactone in rat small intestine. Methods The model of intestine circulation in rats was established. The volume of circulating fluid was corrected by phenol red labeling method and the content of nepetalactone in circulating fluid at different time was determined by HPLC. Results The absorption rate constants Ka of nepetalactone at different concentrations (1.84, 3.68, 3.36 μg.mL-1) were (0.202 8 ± 0.007 0), (0.158 9 ± 0.011 4) and (0.134 2 ± 0.012 2) h-1, and there was a significant difference among the groups (P <0.05). The absorption rate constant of the nepetalactone in the rat duodenum, jejunum and ileum with mass concentration of 3.68μg.mL-1 Ka (0.023 8 ± 0.000 6), (0.012 5 ± 0.000 5) and (0.016 5 ± 0.000 8) h-1, respectively. There were significant differences among the groups (P <0.05). Ligation of bile duct or not, as well as the destruction of intestinal flora, intestinal absorption of nepetalacta little effect. Compared with the control group, the Ka value of P-gp inhibitor group was significantly different (P <0.05). Conclusion The absorption of nepetalactone in the intestine of rats is a first-order kinetic process, and the absorption mechanism is active transport. In the intestine of rats, there is absorption, of which the duodenum is the best absorption site.