Interrelationship between insulin-like growth factor I-induced activation of the Na+/H(+)-antiporter and intracellular Ca(2+)-mobilization in thyroid cells.
Insulin-like growth factor I (IGF-I) increased cytoplamic pH (pHi) and cytoplasmic Ca2+ [( Ca2+]i) in cultured porcine thyroid cells. Inhibition of the Na+/H(+)-antiporter by dimethylamiloride or a reduction of external Na(+)-concentrations attenuates the increases in pHi and [Ca2+]i. The [Ca2+]i response to IGF-I is a pHi-dependent process. IGF-I activates Na+/H(+)-antiporter and alkalinizes thyroid cells. The resulting increase in pHi facilitates the [Ca2+]i response by adjusting the pHi closer to the pHi-optimum of the intracellular Ca(2+)-mobilizing system. One of the biological functions of IGF-I-induced activation of the Na+/H(+)-antiporter is to shift the pHi to an optimal value for the [Ca2+]i response.
Takasu
N
N
Department of Gerontology, Endocrinology and Metabolism, School of Medicine, Shinshu University, Nagano-ken, Japan.
Komiya
I
I
Nagasawa
Y
Y
Asawa
T
T
Shimizu
Y
Y
Yamada
T
T
D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D005452:Fluoresceins; D005456:Fluorescent Dyes; D016257:Fura-2; D006863:Hydrogen-Ion Concentration; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D007700:Kinetics; D017923:Sodium-Hydrogen Exchangers; D013050:Spectrometry, Fluorescence; D013552:Swine; D013961:Thyroid Gland / Q000187:drug effects / Q000378:metabolism*
D002352:Carrier Proteins; D005452:Fluoresceins; D005456:Fluorescent Dyes; D017923:Sodium-Hydrogen Exchangers; C039465:5-dimethylamiloride; D007334:Insulin-Like Growth Factor I; D000584:Amiloride; C043829:2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein; D002118:Calcium; D016257:Fura-2