An electrophysiological study of cultured human pituitary cells.
The electrophysiological properties of tumoral pituitary cells were studied in 4 types of human adenomas including prolactinomas, growth-hormone-secreting tumors, adrenocorticotropin-hormone-secreting adenoma and 'non-functioning' tumors. Only 9% of the cells from prolactinomas and ACTH tumors were excitable but they never elicited spontaneous action potentials. These cells did not respond to substances known to act on the hormone-releasing process (thyreoliberin, dopamine). However, 37% of the cells cultured from growth-hormone-secreting adenomas and from 'non-functioning' tumors displayed action potentials. The action potential was calcium-dependent, i.e., it was blocked by cobalt, nickel and methoxyverapamil and could be recorded in a sodium-free medium. Thyreoliberin triggered action potentials, whereas dopamine and gamma-aminobutyric acid inhibited electrical activity. These results show that human tumoral pituitary cells in culture are able to generate Ca2+-dependent action potentials. The data from growth-hormone-secreting tumors are in good agreement with the stimulus-secretion coupling concept; however, differences in the response of cells cultured from other types of human pituitary tumors suggest that each type of adenoma has specialized membrane properties.
D000200:Action Potentials / Q000187:drug effects; D000236:Adenoma / Q000503:physiopathology*; D002118:Calcium / Q000494:pharmacology; D002478:Cells, Cultured; D004298:Dopamine / Q000494:pharmacology; D004594:Electrophysiology; D006801:Humans; D010902:Pituitary Gland / Q000503:physiopathology*; D010907:Pituitary Hormones / Q000378:metabolism; D010911:Pituitary Neoplasms / Q000503:physiopathology*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D010907:Pituitary Hormones; D005680:gamma-Aminobutyric Acid; D013973:Thyrotropin-Releasing Hormone; D002118:Calcium; D004298:Dopamine