Short-term disappearance of muscarinic cell surface receptors in carbachol-induced desensitization

A rapid carbachol-induced disappearance of muscarinic cell surface receptors was shown using [3H]methyl scopolamine as ligand on intact 108CC15 hybrid cells or rat cerebellar cells. This phenomenon is temperature-dependent, correlated to agonist stimulation and reversible. In these short time periods (less than or equal to 30 min), no change was observed in the total receptor amount measured on membrane preparations. This disappearance of cell surface receptors could represent the first event in cell desensitization which could be followed by receptor recycling in physiological conditions or by receptor degradation if the stimulation by agonists persists, as in long-term regulation.