Ligand Based Approach to L-Type Calcium Channel by Imidazo[2,1-b]thiazole-1,4-Dihydropyridines: from Heart Activity to Brain Affinity

The synthesis, characterization, and functional in vitro assay in cardiac and smooth muscle (vascular and nonvascular) of a series of 4-imidazo[2,1-b]thiazole-1,4-dihydropyridines are reported. To define the calcium blocker nature of the imidazo[2,1-b]thiazole-1,4-DHPs and their selectivity on Ca(v)1.2 and Ca(v)1.3 isoforms, we performed binding studies on guinea pig atrial and ventricular membranes on intact cells expressing the cloned Ca(v)1.2a subunit and on rat brain cortex. To get major insights into the reasons for the affinity for Ca(v)1.2 and/or Ca(v)1.3, molecular modeling studies were also undertaken. Some physicochemical and pharmacokinetic properties of selected compounds were calculated and compared. All the biological data collected and reported herein allowed us to rationalize the structure-activity relationship of the 4-imidazo[2,1-b]thiazole-1,4-DHPs and to identify which of these enhanced the activity at the central level.