title: Multiple types of neurotransmitter binding sites in the rat neuroblastoma B 50 cell line. II. Response of second messenger systems to physiological stimuli in proliferating and differentiated cells.
abstract: The functionality of the alpha 1-, beta-adrenergic and muscarinic cholinergic binding sites of neuroblastoma B 50 is investigated under proliferating and differentiating conditions. In proliferating cells, the stimulation of the alpha 1-adrenergic and muscarinic cholinergic binding sites by their respective agonists causes an increase in both extracellular calcium association with the cells and phosphatidylinositol (PI) turnover; effects usually associated with functional receptors. When the cells are induced to differentiate morphologically with dibutyryl cyclic AMP (db-cAMP), extracellular calcium or a combination of both, the activity of the muscarinic receptor-coupled PI turnover is strictly correlated with the binding affinity of the receptor. This is not the case for the alpha 1-adrenergic receptor stimulation of PI turnover. The latter result, however, may be explained in terms of the intrinsic properties of the inducing agents used to cause neurite extension. The stimulation of the beta-adrenergic binding site with isoproterenol in proliferating cells, both with and without a phosphodiesterase inhibitor present, does not result in cellular cAMP accumulation. In morphologically differentiated cells, only the db-cAMP-induced state exhibits an increase in [3H]adenosine incorporation into cellular cAMP upon isoproterenol stimulation. This happens only in the presence of a phosphodiesterase inhibitor. The data presented in this study are discussed in terms of the affinity of the receptors for their respective ligands and in terms of the intrinsic properties of the inducing agents.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D003994:Bucladesine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation; D002455:Cell Division; D002460:Cell Line; D009474:Neurons / Q000166:cytology*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism
chemical_list: D018377:Neurotransmitter Agents; D010716:Phosphatidylinositols; D003994:Bucladesine; D000262:Adenylyl Cyclases; D002118:Calcium