PT  - JOURNAL ARTICLE
AU  - S Champion
AU  - J Mauchamp
TI  - Muscarinic cholinergic receptors on cultured thyroid cells. II. Carbachol-induced desensitization.
DP  - 1982 Jan 01
TA  - Molecular Pharmacology
PG  - 73--77
VI  - 21
IP  - 1
4099  - http://molpharm.aspetjournals.org/content/21/1/73.short
4100  - http://molpharm.aspetjournals.org/content/21/1/73.full
SO  - Mol Pharmacol1982 Jan 01; 21
AB  - Muscarinic cholinergic receptors were previously characterized on cultured porcine thyroid cells. The receptor number was increased by chronic thyrotropin or prostaglandin E2 treatments [Champion, S., and J. Mauchamp. Mol. Pharmacol. 21:66-72 (1982)]. The long-term effect of carbachol was studied. After chronic treatment with carbachol, cells were completely desensitized to acute carbachol stimulation. This process was blocked by muscarinic antagonists. A complete desensitization was obtained after 6 hr of treatment with 100 microM agonist. Under these conditions the quinuclidinyl benzilate binding capacity of cell homogenates was reduced by 50%. Withdrawal of carbachol allowed the complete restoration of the sensitivity of cells within 6 hr with only a partial recovery of the binding capacity (25%). The complete complement of receptors was obtained after 24 hr of recovery. Desensitization and agonist-induced decrease in receptor number were not affected by cycloheximide, whereas the recovery of both effect and binding sites required active protein synthesis.