Objective To explore the possible mechanism of plantago asiatica L. treating urinary calculus.Methods Forty urine volume sensitive rats were selected by water load method and randomized into blank control group

positive control group

low-dose

middle-dose and high-dose flavonoids groups

8 rats in each group. Rats in every group were given water but fasting. After 15 hours

all rats were given water load normal saline 30 ml / kg. After30 minutes

positive control group were given hydrochlorothiazide tablets 11. 6 mg / kg by gavage; flavonoids low

middle and high dose groups were given total flavonoids of plantago asiatica L. 120

240

480 mg / kg by gavage.Blank control group were given isovolumetric pure water by gavage. On the first day

after administration

pressed lower abdomen to exhaust residual urine in bladder

put rats in metabolic cages

collected 6h urine

compare urine weight at 1

2

4

6 h; and detected the contents of urine Na+

Cl-

and K+. After 7 days of continuous administration

taking acetylcholine and noradrenaline as tool drug

compared the contraction response of bladder and urethral smooth muscles. Results Compared with control group

urine weight and content of urine Na+and Cl-in flavonoids low

middle and high dose groups increased significantly（ P < 0. 05

P < 0. 01）; there was little impact on K+content（ P > 0. 05）. Contraction rate of in vitro bladder smooth muscles and inhibition rate of urethral smooth muscles in flavonoids low

middle and high dose groups were higher than those in control group and positive control group（ P < 0. 01）. Conclusion Total flavonoids of plantago asiatica L. have obvious diuretic effect and could enhance bladder excretion function. Its diuretic and excretive effect might be one of the important mechanisms of plantago asiatica L. treating urinary calculus.