Effects of acetylcholine on inositol 1,4,5-triphosphate formation in cervix uteri myometrial cells of human

AIM: To detect inositol 1,4,5-triphosphate (IP3) formation of pregnant and nonpregnant human myometrial cells induced by acetylcholine (ACh). METHODS: [H-3] IP3 competitive protein binding assay. RESULTS: Basal levels of IP3 in pregnant and nonpregnant human myometrial cells were (82 +/- 9) and (96 +/- 10) nmol . g(-1)(protein), respectively (n = 6). Incubated with ACh 50 mu mol . L-1 for 5 min, IP3 reached the peak levels (109 +/- 11) and (122 /- 15) nmol . g(-1) (protein), respectively (n = 6), but difference of the increments of IP3 in pregnant and nonpregnant women was not significant. Th e increased IP3 induced by ACh was inhibited by atropine(Atr) 1 mu mol , L- 1. CONCLUSION: The basal IP3 level in pregnant cervix myometrial cells was higher than that in nonpregnant women. ACh increased the IP3 formation.