[Cardiodepressive action of bencyclan (author's transl)]

In the isolated guinea pigs atria as well as in anaesthetized cats and dogs we studied the cardiovascular effects of bencyclan. The following results were found: 1.) Bencyclan causes a dose-dependent diminution of the force of contraction, the maximal rate of rise of contraction, and the frequency of the isolated atria, while the functional refractory period is prolonged. 2.) The negative inotropic effect of bencyclan can be antagonized in the isolated atria by increasing Ca+++ -concentrations. 3.) In the isolated left atria the effect of orciprenaline is unchanged while the effect of serotonin is diminished by bencyclan. 4.) In the anaesthetized cat 5 mg/kg of bencyclan cause a significant decrease of blood-pressure and contractility. While the fall of blood-pressure is reversed within a few minutes, the contractility is diminished for a longer time. 5.) 2 of 10 cats and 2 of 3 dogs died within a few minutes when 5 mg/kg bencyclan and 1 mg/kg propranolol were injected within an interval of 15 minutes. 6.) Pretreatment with 20 mg/kg propranolol i.m. does not increase the acute toxicity of bencyclan in mice significantly.