RESUMEN
Aim To explore the diuretic effect, diuretic mechanism and pharmacokinetics of Phytolacca acinosa Roxb., and clarify its "quantity-time-effect" relationship.Methods Firstly, qualified rats were modeled by water load model, given different doses of Phytolacca acinosa Roxb.aqueous extract, then the diuretic effect was investigated.Secondly, Western blot was used to detect the protein expression of aquaporins AQP2, AQP4 and the angiotensin II receptors ATGR1, ATGR2, and renin in the RAAS system in kidney tissues.Thirdly, the established LC-MS/MS biological analysis method was used to detect the esculentoside A(EsA)content in the plasma, calculate the pharmacokinetic parameters and analyze the correlation between the blood concentration and the drug effect.Results The water load model was successfully established.Compared with the model group, hydrochlorothiazide had a significant diuretic effect(P<0.01).Low, medium and high dose groups of Phytolacca acinosa Roxb.all had obvious diuretic effects(P<0.01), EsA also had a significant diuretic effect(P<0.05).Phytolacca acinosa Roxb.aqueous extract and EsA significantly down-regulated the expression of AQP2, AQP4, ATGR1 and renin protein.The pharmacokinetic results showed that the Cmax and AUC0-t of EsA in the plasma of rats in the low, medium, and high dose groups of aqueous extract increased with the increase of the dose.Conclusions Phytolacca acinosa Roxb.had a diuretic effect, which is related to inhibiting the expression of aquaporins AQP2 and AQP4 and inhibiting the expression of angiotensin II type 1 receptor and renin, thereby inhibiting the reabsorption of renal tubules and collecting ducts.