Rat cardiac muscarinic receptors. II. Influence of thyroid status and cardiac hypertrophy
Robberecht, P.; Waelbroeck, M.; Claeys, M.; Huu, A.N.; Chatelain, P.; Christophe, J.
Molecular Pharmacology 21(3): 589-593
1982
ISSN/ISBN: 0026-895X PMID: 6213844 Document Number: 196424
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 concentrations 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. Cardiac hypertrophy provoked by aortic stenosis also led to a decreased concentration of low-affinity binding sites without affecting the concentration of high-affinty binding sites.