Role of pertussis toxin sensitive G proteins in the alpha 1 adrenergic receptor but not in the thyrotropin receptor mediated activation of membrane phospholipases and iodide fluxes in FRTL-5 thyroid cells.
The regulation of thyroid hormone formation by thyrotropin and norepinephrine involves the activation of both phospholipases C and A2. When FRTL-5 cells are incubated with 10(-10)M pertussis toxin for 4 to 20 h, the stimulation of iodide efflux by norepinephrine is inhibited by 50 to 70%. At the same toxin concentration the norepinephrine induced increase in cytosolic Ca2+ is unaffected; however upon 20 h pretreatment with 10(-9)M pertussis toxin a 30% inhibition is observed. By contrast, the pertussis toxin treatment had no effect on the increase in iodide efflux or in cytosolic Ca2+ levels induced by thyrotropin. Our data suggest that two GTP binding proteins sensitive to pertussis toxin are involved in the alpha 1 adrenergic but not in the thyrotropin induced activation of the signal transduction mechanisms leading to iodide efflux in FRTL-5 cells.
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D003600:Cytosol / Q000378:metabolism; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000502:physiology*; D007454:Iodides / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology; D037342:Pertussis Toxin; D010740:Phospholipases / Q000378:metabolism*; D010741:Phospholipases A / Q000378:metabolism; D051381:Rats; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D011989:Receptors, Thyrotropin / Q000502:physiology; D013961:Thyroid Gland / Q000187:drug effects / Q000201:enzymology*; D013972:Thyrotropin / Q000494:pharmacology; D010738:Type C Phospholipases / Q000378:metabolism; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D007454:Iodides; D011942:Receptors, Adrenergic, alpha; D011989:Receptors, Thyrotropin; D010566:Virulence Factors, Bordetella; D013972:Thyrotropin; D037342:Pertussis Toxin; D010740:Phospholipases; D010741:Phospholipases A; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D002118:Calcium; D009638:Norepinephrine