The Impact Of Rapamycin In Combination With Atorvastatin On Each Other’s Intestinal Absorption Mediated By Expression Of P-glycoprotein

ObjectiveTo establish a method of high-performance liquid chromatographymethod for measuring the concentrations of rapamycin and atorvastatin. Toexplore the effects of rapamycin and atorvastatin on the intestinal absorbtionby in vitro dispersion tests used the everted gut sac model in rat combining insitu intestinal absorption studies chosen the single pass intestinal perfusionmodel, and to investigate the effect of the expression of P-glycoprotein bywestern blot.MethodsIn vitro used the everted gut sac model,24Wistar rats were divided intothree groups: RAPA group (n=8), ATV group(n=8) and RAPA+ATV group(n=8).The everted intestine was slipped off the glass rod and placed in a flat dishcontaining the Krebs-Ringer’s buffer oxygenated with O2/CO2(95%/5%) at37℃. Rapamycin was added into Krebs-Ringer’s for RAPA group, atorvastatinwas added for ATV group and rapamycin together with atorvastatin wasadded for RAPA+ATV group.In situ intestinal absorption studies chosen the single pass intestinalperfusion model,24rats were divided into three groups: RAPA group (n=8), ATV group(n=8) and RAPA+ATV group(n=8). A proximal end was carefullyexposed and cannulated on two ends with flexible PVC tubing. Samples wasassayed by HPLC.In addition, rats of in situ absorption model were divided into solventgroup(n=6), RAPA group (n=6), ATVgroup (n=6) and RAPA+ATV group(n=6).The intestinal mucosas of the rats were scraped two hours afteradministration. P-glycoprotein was extracted and evaluated by western blot.ResultsIn vitro, the concentration of rapamycin and atorvastatin in RAPA+ATVgroup were higher than those in other groups(P<0.05) after0.5,1and2hour.In situ, the values of P%and Pappof rapamycin and atorvastatin in RAPA+ATVgroup were also higher than those in other groups(P<0.05) after0.5,1and2hour. With the analyses of western blot, the intensity of P-gp in RAPA groupand ATV group were weaker compared with the solvent group, and theintensity of P-gp in RAPA+ATV group was weakest of all. The relative intensityof P-gp in RAPA+ATV group was lower compared with RAPA group and ATVgroup(P<0.05).ConclusionsThe discreased expression of p-glycoprotein might contribute to theincreased absorption of rapamycin and atorvastatin in the intestinal.