PT  - JOURNAL ARTICLE
AU  - ESAM EL-FAKAHANY
AU  - ELLIOTT RICHELSON
TI  - Phenoxybenzamine and Dibenamine Interactions with Calcium Channel Effectors of the Muscarinic Receptor
DP  - 1981 Nov 01
TA  - Molecular Pharmacology
PG  - 519--525
VI  - 20
IP  - 3
4099  - http://molpharm.aspetjournals.org/content/20/3/519.short
4100  - http://molpharm.aspetjournals.org/content/20/3/519.full
SO  - Mol Pharmacol1981 Nov 01; 20
AB  - Phenoxybenzamine and dibenamine were more effective at blocking muscarinic acetylcholine receptor-mediated cyclic GMP formation in mouse neuroblastoma cells (clone N1E-115) than at blocking radiolabeled antagonist binding to the muscarinic receptors of these cells. High calcium concentrations antagonized the effects of these 2-halogenoethylamines on the cyclic GMP response but not on the receptor binding. In addition, the apparent equilibrium dissociation constant for carbachol and the muscarinic receptor determined in the biological assay with the use of the 2-halogenoethylamines was several-fold greater than that determined by radioligand binding assays. These results suggest that phenoxybenzamine and dibenamine interact with calcium channels in addition to muscarinic receptors, and on the basis of these and other results, we propose a scheme for the interactions of agonists and antagonists with muscarinic receptors and their effectors (calcium channels).