The contrasting role of calcium influx in secretion induced by cell swelling can differentiate normal and tumor-derived rat pituitary cells.
We have evaluated whether cell swelling may be a generally useful technique to differentiate normal and neoplastic pituitary cells, making the comparison between normal lactotrophs and thyrotrophs and tumor-derived GH4C1 and MMQ cells. With 1.5 mM medium Ca2+, cell swelling induced by osmotically equivalent stimuli, 27% medium hyposmolarity or 80 mM isotonic urea, caused a prompt increase in both intracellular Ca2+ and hormone secretion by all cell types. Depletion of medium Ca2+ abolished the cell swelling-induced increase in intracellular Ca2+ in all cell types and hormone secretion in the tumor-derived cells. However, it enhanced hormone secretion in normal cells. The critical role of Ca2+ influx in osmotically induced secretion in neoplastic, but not normal, pituitary cells may reflect some fundamental alteration in the intracellular transduction system in tumor cells.
Department of Medicine, Oregon Health Sciences University, Portland 97201.
N
N
Sato
M
M
Murakami
X B
XB
Wang
M A
MA
Greer
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003470:Culture Media; D004563:Electrochemistry; D007552:Isotonic Solutions; D009994:Osmolar Concentration; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000378:metabolism*; D010907:Pituitary Hormones / Q000378:metabolism; D010911:Pituitary Neoplasms / Q000378:metabolism* / Q000473:pathology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D012016:Reference Values; D014407:Tumor Cells, Cultured; D014508:Urea / Q000494:pharmacology
D003470:Culture Media; D007552:Isotonic Solutions; D010907:Pituitary Hormones; D014508:Urea; D011188:Potassium; D002118:Calcium