title: Electrical responses of cultured porcine thyroid cells to adrenergic agents.
abstract: The membrane potential of cultured porcine thyroid follicular cells depolarized by up to 20 mV from the resting value of about -73 mV on exposure to beta-adrenoceptor agonists. A similar response was induced by TSH or dibutyryl cyclic AMP. alpha-Adrenoceptor agonists were without effect. The receptor subtype was shown to be (at least predominantly) beta 2 by the order of potency for beta-agonists (isoprenaline approximately equal to fenoterol much greater than adrenaline greater than noradrenaline) and by the relative potency of selective beta-antagonists (ICI 118,551 much greater than atenolol). The alpha-agonist phenylephrine had no effect on the TSH response but weakly inhibited the beta-agonist response. Rather than a physiological antagonism between alpha- and beta-adrenoceptor-mediated responses, this effect was shown to be due to the weak beta-antagonist effect of phenylephrine since the alpha-antagonist phentolamine failed to potentiate the depolarizing response to the mixed agonist noradrenaline, and also failed to block the inhibitory action of phenylephrine on the beta-agonist effect. Sensitivity to beta-agonist was enhanced by omission of serum from the culture medium and reduced by exposure to beta-agonists or a high concentration of TSH or dibutyryl cyclic AMP.
authors.forename: P A
authors.initials: PA
authors.lastname: McGrath
authors.forename: J R
authors.initials: JR
authors.lastname: Bourke
authors.forename: G J
authors.initials: GJ
authors.lastname: Huxham
authors.forename: S W
authors.initials: SW
authors.lastname: Manley
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000494:pharmacology; D005280:Fenoterol / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D013552:Swine; D013961:Thyroid Gland / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D013972:Thyrotropin / Q000494:pharmacology
chemical_list: D000318:Adrenergic beta-Agonists; D005280:Fenoterol; D003994:Bucladesine; D013972:Thyrotropin; D007545:Isoproterenol; D009638:Norepinephrine; D004837:Epinephrine