title: Effect of lidocaine on alpha 1-adrenoceptors in cultured neonatal rat cardiocytes.
abstract: The effect of lidocaine on alpha 1-adrenoceptors in cultured neonatal rat ventricular cardiocytes was studied by binding assay. When the cells were cultured in the presence of lidocaine, the binding of (+/-)-beta-([125I]iodo-4-hydroxyphenyl)-ethyl-aminomethyl-tetralone to the cells increased in a concentration- and time-dependent manner. The effect was due to an increase in maximum binding but not due to a change in the dissociation constant for the ligand. The increased number of alpha 1-adrenoceptors returned to the control level after culturing the cells without lidocaine. The stimulating effect on the number of alpha 1-adrenoceptors of lidocaine was also observed in the presence of norepinephrine. Other class I antiarrhythmic drugs such as procainamide. disopyramide, mexiletine and flecainide increased the number of alpha 1-adrenoceptors in the cells. These results suggest that cardiac responsiveness mediated by alpha 1-adrenoceptors is increased by class I antiarrhythmic drugs.
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D001667:Binding, Competitive; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D006321:Heart / Q000187:drug effects*; D007457:Iodine Radioisotopes; D008012:Lidocaine / Q000494:pharmacology*; D008297:Male; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D009638:Norepinephrine / Q000494:pharmacology; D010627:Phenethylamines / Q000737:chemistry / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects* / Q000378:metabolism; D044024:Tetralones; D015854:Up-Regulation
chemical_list: D000317:Adrenergic alpha-Antagonists; D000889:Anti-Arrhythmia Agents; D007457:Iodine Radioisotopes; D010627:Phenethylamines; D018340:Receptors, Adrenergic, alpha-1; D044024:Tetralones; C048008:2-(beta-(3-iodo-4-hydroxyphenyl)ethylaminomethyl)tetralone; D008012:Lidocaine; D009638:Norepinephrine