Cardiovascular effects of 1-benzylimidazole

A derivative of imidazole, 1-benzylimidazole [(1-phenylmethyl)-H-imidazole], was found to have strong cardiotonic activity. In isolated ventricular strips of rabbits, 6.3 times 10(-5) M 1-benzylimidazole (BI) increased contractile force by 100%, and in the intact cat, 0.5 mg/kg of BI increased cardiac output by 30 to 40%. The increase was maintained in both preparations for 5 to 30 minutes. Heart rate was not changed in the atropine-pretreated cat. Basic cycle length, recorded intracellularly in rabbit sinoatrial nodal cells, was increased by 8%. Since BI had many actions similar to the cardiac glycosides, including the absence of effects on rate and resistance to adrenergic beta blockers, it was of interest to determine whether BI and ouabain could interact and modify, or enhance their respective actions. In combination, it was found that ouabain and BI had summative effects on contractility and maintained the frequency-force relationships. In this respect, the action of BI is similar to that of glucagon and Ca++, but not to that of the catecholamines.