effects of acetylcholine on inositol 145triphosphate formation in cervix uteri myometrial cells of human aim to detect inositol 145triphosphate ip3 formation of pregnant and nonpregnant human myometrial cells induced by acetylcholine achmethods 3h ip3 competitive protein binding assayresults basal levels of ip3 in pregnant and nonpregnant human myometrial cells were 82 9 and 96 10 nmolg1 protein respectively n 6 incubated with ach 50 mumoll1 for 5 min ip3 reached the peak levels 109 11 and 122 15 nmolg1 protein respectively n 6 but difference of the increments of ip3 in pregnant and nonpregnant women was not significant the increased ip3 induced by ach was inhibited by atropine atr 1 mumoll1conclusion the basal ip3 level in pregnant cervix myometrial cells was higher than that in nonpregnant women ach increased the ip3 formation