Objective     To investigate the relationship between IP

3

/Ca

2+

signal transduction process and the changes of intracellular calcium in detrusor cells in rats.      Methods     The model of overactive detrusor (OAD) was successfully established in female Wistar rats. Intracellular calcium fluorescence intensity of cultured detrusor cells in OAD rats and detrusor stability (DS) rats was measured by laser scanning confocal microscopy (LSCM). After pretreated by 10

-5

mol/L IP

3

alone or with its inhibitor heparin

the intracellular calcium f

luorescence intensity of cultured detrusor cells of DS rats in Ca

2+

-contained and Ca

2+

-free solutions was measured with LSCM.      Results     Intracellular calcium fluorescence intensity of cultured detrusor cells in OAD rats was stronger than that of DS rats (P0.01). After pretreated by 10

-5

mol/L IP

36

the intracellular calcium fluorescence intensity in cultured detrusor cells of DS rats was obviously enhanced as compared with that before pretreatment (P0.01)

and stronger in the cells cultured in Ca

2+

-contained solution than that in Ca

2+

-free solution (P0.01). Heparin could inhibit the intracellular calcium fluorescence intensity enhanced by IP

3

.      Conclusion     The increase of intracellular free calcium concentration in detrusor cells caused by IP

3

may be one of important factors inducing detrusor instability.