Affinity of 2-(tetrahydroisoquinolin-2-methyl)- and 2-(isoindolin-2-ylmethyl)imidazolines for α-adrenoceptors. Differential affinity of imidazolines for the [3H]idazoxan-labeled α2-adrenoceptor vs the [3H]yohimbine-labeled site

Article abstract of DOI:10.1021/jm00164a021

A series of 2-(tetrahydroisoquinolin-2-ylmethyl)- and 2-(isoindolin-2-ylmethyl)imidazolines were prepared and tested for α₁- and α₂-adrenoceptor affinity with radioligand binding. Several compounds, 5-fluoro- (5h), 5-chloro- (5j), 5,8-dimethoxy- (5r), and 5,8-dimethoxy-1-methyl- (5s) 2-(tetrahydroisoquinolin-2-ylmethyl)imidazoline, were found to be selective α₂-adrenoceptor ligands on the basis of displacement of [³H]yohimbine from rat cerebral cortical membranes. One compound, 2-[(8-chloro tetrahydroisoquinolin-2-yl)methyl]imidazoline (5m), showed a 36-fold difference in affinity for the [³H]idazoxan-labeled α₂-adrenoceptor relative to the [³H]yohimbine-labeled site, which may be evidence for α₂-adrenoceptor subtypes.