In vitro absorption mechanism of strychnine and the transport interaction with liquiritin in Caco-2 cell monolayer model

To study the effect of liquiritin (Liq) on the transport of strychnine (Str) in Caco-2 cell monolayer model, the transport parameters of Str, such as apparent permeability coefficient (P_{app (B→A)} and P_{app (A→B)} ) and cumulative transport amount (TR_cum), were determined and comparatively analyzed when Str was used solely and co-used with Liq.  The effect of drug concentrations, conveying times, P-glycoprotein (P-gp) inhibitor verapamil and conveying liquor pH values on the transport of Str were also investigated.  The results indicated that the absorption of Str in Caco-2 cell monolayer model was well and the passive transference was the main intestinal absorption mechanism of Str in the Caco-2 monolayer model, along with the excretion action mediated by P-gp.  Liq enhanced the absorption of Str.  Meanwhile, conveying liquor pH value had significant influence on the  excretion transport of Str.