Regulation by chronic drug administration of neuronal and cardiac calcium channel, beta-adrenoceptor and muscarinic receptor levels.
Chronic administration of atropine (40-100 mg/kg, 23 days) produced a 29-33% increase in muscarinic receptors, measured by [3H]quinuclidinyl benzilate binding, in rat brain. Diisopropyl phosphorofluoridate (0.9 mg/kg, 14 days) produced a 35% decrease in muscarinic receptors. Propranolol administration (800 micrograms/kg/hr, 10 days) increased beta-adrenoceptors, measured by [3H]dihydroalprenolol binding, by 69 and 50% in brain and heart respectively. Isoproterenol administration (800 micrograms/kg/hr, 10 days) produced a 50% reduction in cardiac beta-adrenoceptors but did not alter brain receptors. These drug treatments were without effect on binding of the Ca2+ channel ligands, [3H]nimodipine and [3H]nitrendipine, to brain or heart respectively. However, chronic administration of nifedipine for 20 days (36 and 360 micrograms/kg/hr) did produce down-regulation of both cardiac and neuronal Ca2+ channels and a similar down-regulation of beta-adrenoceptors. Co-regulation of Ca2+ channels and neurotransmitter receptors may occur but may not be an automatic consequence of either receptor or channel regulation.
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001921:Brain / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism*; D006321:Heart / Q000187:drug effects*; D007473:Ion Channels / Q000187:drug effects*; D008297:Male; D009543:Nifedipine / Q000494:pharmacology; D009568:Nitrendipine / Q000378:metabolism; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000032:analysis / Q000187:drug effects*; D011976:Receptors, Muscarinic / Q000032:analysis / Q000187:drug effects*
D007473:Ion Channels; D011943:Receptors, Adrenergic, beta; D011976:Receptors, Muscarinic; D001285:Atropine; D009568:Nitrendipine; D011433:Propranolol; D009543:Nifedipine; D002118:Calcium