Early in vitro stimulation of endometrial (Na+-K+)-ATPase by estradiol

Physiological concentrations of estradiol (2-10 nM) can approximately double the activity of the endometrical (Na+-K+)-ATPase in immature mammalians. This stimulation in vitro is optimum as early as 30 minutes after contact of uteri with the hormone and it is not inhibited by incubation with cycloheximide. Analogues of 17 beta estradiol have little effect on the enzyme activity, but another steroid hormone testosterone, is capable of a similar activating effect.