Effects of Radix Isatidis and contained indigo and indirubin on organic cation transporters OCT1 and OCT2 in mouse kidney / 中国药理学与毒理学杂志

ABSTRACT

OBJECTIVE To investigate the effect of Radix Isatidis and its constituents indigo and in?dirubin on two principal subtypes of organic cation transporters(OCT)OCT1,OCT2 in vivo in mice. METHODS Decoction of Radix Isatidis (DRI) 1.6 and 6.4 g · kg-1,granules of Radix Isatidis (GRI) 0.615 and 2.460 g·kg-1,indigo 0.008 and 0.640 mg·kg-1 and indirubin 0.0192 and 1.536 mg·kg-1 were ig given to NIH mice(60 mice per group),twice a day for 5 d. Four control groups were set up,including the vehicle of water,0.5% sodium carboxymethyl cellulose(CMC),additives of sucrose plus dextrin (1.5 g · kg-1)and positive control quinidine(0.025 g · kg-1). Sixty minutes after the last dosing,all the mice were iv given metformin(Met)5 mg·kg-1,and at 1.0,2.5,5.0,7.5,10.0 and 20.0 min after Met iv,10 mice in each group were sacrificed to collect whole blood and kidneys respectively. The right kidney was homogenized for Met accumulation test and the left one used to extract total RNA for analysis of OCT1 and OCT2 mRNA expressions by real-time PCR. The contents of Met in sera and kidneys were quantified by HPLC. Major pharmacokinetic parameters of Met in sera were analyzed by pharmacokinetic software(DAS 2.0). RESULTS There was no significant difference between water control group,0.5%CMC group and sucrose plus dextrin group in any examined item. Compared with vehicle control group (water and 0.5%CMC group),all the related pharmacokinetic parameters in DRI 6.4 g · kg- 1,GRI 2.46 g · kg-1,indigo 0.640 mg · kg-1 and indirubin 1.536 mg · kg-1 groups were changed significantly (P<0.05,P<0.01). The elimination half time (t1/2β) was prolonged 13%-97%,volume of distribution reduced by 13%-72%,clearance(Cl)reduced by 9%-65%,and the area under the concentration-time curve (AUC0-20 min) increased by 13%-135%. AUC0-20 min obtained from renal Met accumulations was significantly increased(P<0.01)while Met uptake by kidney slices was reduced(P<0.05,P<0.01). The expressions of OCT1 and OCT2 mRNA were obviously down-regulated(P<0.05,P<0.01). CONCLUSION The mouse renal OCT1 and OCT2 are significantly inhibited by DRI,GRI,indigo and indirubin. The inhibitory effect of Radix Isatidis on OCT1 and OCT2 probably arises from indigo and indirubin contained.