Effects of divaside on cardiac contractility, excita-bility, automaticity, refractory period and surface electrogram on cat papillary muscles

The direct effects of divaside on the contractility, excitability, auto-maticity and functional refractory pe-riod were studied in comparison with those of ouabain. In addition, electrical and mechanical behaviors were observed simultaneously before and after divaside and ouabain intoxications. 1) Divaside and ouabain increased car-diac contractility significantly and dose-dependently. 2) Divaside (0.365 or 3.65 mg/l) and ouabain (0.292 0r 2.92 mg/l) shortened functional refractory period significantly. But divaside (0.0365 mg/l) and ouabain (0.0292 mg/l) had no signifi-cant effect. 3) Divaside (0.0365 0r 0.365 mg/l) and ouabain (0.0292 0r 0.292 mg/l) exerted no significant influence on excit-ability. Excitability was slightly increased and signifcantly decreased during early and late intoxication, respectively. 4) Di-vaside (0.365 mg/l) and ouabain (0.292 mg/l) increased automaticity induced by adrenaline. 5) An O wave and after con-traction were seen after divaside and oua-bain intoxications.