Cytoplasmic pH in cultured porcine thyroid cells: alkalinization by epidermal growth factor |
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| Authors: | N Takasu Y Nagasawa I Komiya Y Shimizu T Yamada |
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| Institution: | Department of Gerontology, Endocrinology and Metabolism, School of Medicine, Shinshu University, Nagano-ken, Japan. |
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| Abstract: | 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. |
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