Cytoplasmic pH in cultured porcine thyroid cells: alkalinization by epidermal growth factor.
We studied the effects of epidermal growth factor (EGF), thyroid-stimulating hormone (TSH) and amiloride on cytoplasmic pH (pHi) in cultured porcine thyroid cells. We used 2',7'-bis(2-carboxyethyl)-5- (and 6-)carboxyfluorescein (BCECF), an internalized fluorescent pH indicator, to measure pHi. EGF stimulated thyroid cell alkalinization and proliferation, which were blocked by amiloride. EGF-stimulated thyroid cell alkalinization depended on extracellular Na+ concentrations. EGF stimulation resulted in an activation of Na+/H+ exchange, which alkalinized the cells. The results indicated that Na+/H+ exchange or cell alkalinization might function as a transmembrane signal transducer in the action of EGF. In the present system, TSH did not stimulate alkalinization or proliferation.
Takasu
N
N
Department of Gerontology, Endocrinology and Metabolism, School of Medicine, Shinshu University, Nagano-ken, Japan.
Nagasawa
Y
Y
Komiya
I
I
Shimizu
Y
Y
Yamada
T
T
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D005452:Fluoresceins; D005456:Fluorescent Dyes; D006863:Hydrogen-Ion Concentration; D011522:Protons; D015398:Signal Transduction; D012964:Sodium / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers; D013552:Swine; D013961:Thyroid Gland / Q000187:drug effects / Q000378:metabolism*; D013972:Thyrotropin / Q000494:pharmacology
D002352:Carrier Proteins; D005452:Fluoresceins; D005456:Fluorescent Dyes; D011522:Protons; D017923:Sodium-Hydrogen Exchangers; D004815:Epidermal Growth Factor; D000584:Amiloride; C043829:2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein; D013972:Thyrotropin; D012964:Sodium