Figure 1

Inhibitory effect of 17α- and 17β-E2 on spontaneous uterine contractile activity of rats in diestrus. A) The vehicle utilized to dissolve each estradiol, ethanol (ETOH 0.1%), did not significantly modify (P > 0.05) the spontaneous contractility. 17α- and 17β-E2 induce inhibition of contractile activity. Note their different efficacy when they are added at the same concentration (20 μM). B) Concentration-response curves to 17α- and 17β-E2 on spontaneous contractility, which were significantly different (P < 0.0005) between them. Each point represents the mean ± SEM of six independent experiments. Statistical significance between concentrations: *P < 0.005, **P < 0.0005. The effect induced by both estradiol isomers at all concentrations tested were significantly different (P < 0.0005) from the vehicle control.