Dependence of beta-adrenergic responsiveness on thyroid state of male rats.
The dose of thyroxine (0-150 micrograms/kg body weight) administered subcutaneously daily to surgically thyroidectomized male rats was correlated significantly with their metabolic activity as assessed by rate of oxygen consumption and colonic temperature. There was a significant dose-dependent increase in total serum thyroxine, triiodothyronine and reverse-triiodothyronine concentrations with increasing doses of thyroxine administered. The cardiostimulatory response to administration of isoprenaline (8 micrograms/kg body weight s.c.) was also correlated directly with the dose of thyroxine administered. The concentration of cardiac beta-adrenoceptors in these animals was correlated significantly with total serum thyroxine and triiodothyronine concentrations, basal heart rate, and the chronotropic response to administration of isoprenaline.
D000818:Animals; D006339:Heart Rate / Q000187:drug effects; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000502:physiology*; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D013961:Thyroid Gland / Q000502:physiology*; D013963:Thyroid Hormones / Q000097:blood; D013965:Thyroidectomy; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D013963:Thyroid Hormones; D014284:Triiodothyronine; D007545:Isoproterenol; D013974:Thyroxine