title: Rat cardiac muscarinic receptors. II. Influence of thyroid status and cardiac hypertrophy.
abstract: The effects of the thyroid state and of aortic stenosis on muscarinic cholinergic binding sites in heart membranes were compared (with proper controls) by simultaneously determining total and high-affinity binding sites and estimating low-affinity binding sites by difference. Hyper- and hypothyroidism induced decreased and increased concentration of high-affinity agonist binding sites, respectively, supporting the hypothesis that these sites were directly regulated by thyroid hormones. This was not the case for low-affinity binding sites, as they decreased in number in both hyper- and hypothyroidism. In hyperthyroid rats, this decreased number of low-affinity binding sites could be due to the rapidly developing cardiac hypertrophy. Indeed, cardiac hypertrophy provoked by aortic stenosis led also to a decreased concentration of low-affinity binding sites without affecting the concentration of high-affinity binding sites.
mesh_terms: D000818:Animals; D006332:Cardiomegaly / Q000378:metabolism*; D006980:Hyperthyroidism / Q000378:metabolism; D007037:Hypothyroidism / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011950:Receptors, Cholinergic / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000378:metabolism*; D013961:Thyroid Gland / Q000502:physiology*
chemical_list: D011950:Receptors, Cholinergic; D011976:Receptors, Muscarinic