A New, Nongenomic Estrogen Action: The Rapid Release of Intracellular Calcium*

We have investigated the effects of steroids on the intracellular calcium ion concentration [Ca2+]i in chicken granulosa cells obtained from the two largest preovulatory follicles of laying hens. [Ca2+]i was measured in cells loaded with the Ca(2+)-responsive fluorescent dye fura-2. The resting [Ca2+]i in these cells was 100 +/- 5 nM. There was an immediate (i.e. less than 5 sec) 4- to 8-fold increase in [Ca2+]i in all of the 76 cells examined after the addition of 10(-7) M estradiol-17 bdta. Estradiol-17 beta was effective between 10(-10)-10(-6) M. Estradiol-17 alpha, estrone, and estriol (10(-8)-10(-6) M) were as effective as estradiol-17 beta, but the progestins, pregnenolone, and progesterone, and the androgens, testosterone, androstenedione, or 5 alpha-dihydrotestosterone were ineffective at concentrations up to 10(-5) M. The prompt estradiol-17 beta-induced [Ca2+]i spike was not affected by incubating the cells in Ca(2+)-free medium containing 2 mM EGTA or by pretreating them with the Ca2+ channel b...