Influence of Astragalus extract on the absorption of TMP in rat's small intestine

OBJECTIVE To investigate the absorption kinetics of tetramethylpyrazine(TMP) at small intestine of rats and the influence of concentration and Astragalus extract on the absorption kinetics and the changes of the related parameters.METHODS Using rat's in vivo intestinal circulation experiment and HPLC to investigate the effects of TMP's absorption at small intestine of rats,and investigate the stimulative effect of Astragalus extract on the absorption of TMP.RESULTS The absorptive rate constants(K) of TMP at the concentration of 0.2,0.4,0.8 mg·mL-1 were(0.243 4±0.001 3),(0.185 6±0.001 3),(0.074 6±0.003 9)h-1;while adding different quantity of Astragalus extract to the concentration of 0.2 mg·mL-1 of TMP,the K of TMP was(0.246 4±0.004 6),(0.271 7±0.002 3),(0.289 4±0.001 3),(0.244 2±0.011 4)h-1.CONCLUSION Along with the decrease of the concentration,the absorption rate of TMP was increased,the absorption of TMP was first-order process.Besides the passive diffusion mechanism,facilitated diffusion and active transport may also take part in the transport process;Astragalus extract could promote the absorption of TMP at small intestine of rats,the concentration of Astragalus extract had some effects on the absorption of TMP.