RAT CARDIAC MUSCARINIC RECEPTORS .2. INFLUENCE OF THYROID STATUS AND CARDIAC-HYPERTROPHY

  • 1 January 1982
    • journal article
    • research article
    • Vol. 21  (3) , 589-593
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 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.