Generation of hydrogen peroxide in cultured porcine thyroid cells: synergistic regulation by cytoplasmic free calcium and protein kinase C.
This study set out to elucidate the mechanism by which H2O2 generation is regulated in cultured porcine thyroid cells. We monitored continuously the effects of the calcium ionophore A23187 and the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) on H2O2 generation, using homovanillic acid and horseradish peroxidase. A23187 and TPA stimulated H2O2 generation. A23187 increased cytoplasmic free calcium and TPA activated protein kinase C. Generation of H2O2 is therefore regulated by cytoplasmic free calcium and protein kinase C. Exposure to A23187 or TPA augmented further the stimulation of H2O2 generation by TPA or A23187 respectively. Thus A23187 and TPA, by increasing cytoplasmic free calcium and activating protein kinase C respectively, synergistically activate H2O2 generation.
Takasu
N
N
Department of Gerontology, Endocrinology and Metabolism, School of Medicine, Shinshu University, Nagano-ken, Japan.
Yamada
T
T
Shimizu
Y
Y
Nagasawa
Y
Y
Komiya
I
I
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D004357:Drug Synergism; D006861:Hydrogen Peroxide / Q000096:biosynthesis*; D011493:Protein Kinase C / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013961:Thyroid Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
D000001:Calcimycin; D006861:Hydrogen Peroxide; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium