Open AccessHormonal activation of ionic currents in follicle-enclosed Xenopus oocytes.
Author(s) -
Richard M. Woodward,
Ricardo Miledi
Publication year - 1987
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.84.12.4135
Subject(s) - medicine , endocrinology , forskolin , gonadotropin , xenopus , biology , adenosine , human chorionic gonadotropin , ovarian follicle , oocyte , follicular phase , ovulation , second messenger system , chemistry , microbiology and biotechnology , receptor , hormone , stimulation , biochemistry , embryo , gene
Membrane currents were recorded, using the voltage clamp technique, from Xenopus laevis oocytes still surrounded by their enveloping follicular and epithelial cells. Exposure of the follicles to mammalian gonadotropins elicited a current generated largely by an increase in membrane K+ conductance. The gonadotropin response resembled responses elicited by adenosine and catecholamines in the same follicle, but was not blocked by purinergic or catecholaminergic antagonists. The gonadotropin-induced currents were potentiated by the adenylate cyclase activator forskolin and by phosphodiesterase inhibitors; similar currents were elicited in the same follicle by intraoocyte injection of cAMP, which indicates a role for this second messenger in the response mechanism. Gonadotropin responses were either abolished or substantially reduced after treatments that remove the ovarian epithelial and follicular cells. Our experiments suggest that the gonadotropin receptors, and the K+ channels they regulate, reside in the follicular cells.