Quantitative changes in beta-adrenergic responses of isolated atria from hyper- and hypothyroid rats.
Concentration-response curves for the chronotropic and inotropic effects of isoprenaline, in the absence and presence of propranolol, were obtained on heart atria isolated from normo- or dysthyroid rats. Hyperthyroidism increased the chronotropic potency and efficacy of the beta-adrenergic agonist. The results are compatible with the view that thyroid hormone increases the density of functional beta-adrenoceptors in cardiac pacemaker tissue.
D000818:Animals; D004305:Dose-Response Relationship, Drug; D006325:Heart Atria / Q000378:metabolism*; D006339:Heart Rate / Q000187:drug effects; D006980:Hyperthyroidism / Q000503:physiopathology*; D007037:Hypothyroidism / Q000503:physiopathology*; D007545:Isoproterenol / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011941:Receptors, Adrenergic / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism*; D014284:Triiodothyronine / Q000494:pharmacology
D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D014284:Triiodothyronine; D011433:Propranolol; D007545:Isoproterenol