Zusammenfassung
Der Einfluß von Tocainid auf die durch Epinephrin (0,2 µg/ml) gesteigerte Automatie der Purkinjefaser wurde in vitro mit der Mikroglaselektrodentechnik untersucht. Bei einer Konzentration von 5 und 10 µg/ml Tocainid resultiert eine Verlängerung der Periodendauer zwischen 10,6% und 34,9% bzw. 26,3% und 108,7%. Repetitive Reizbildung im Ventrikelmyokard wurde durch Erzeugung eines Potentialgradienten im Papillarmuskel induziert und die Aktionspotentiale mit Mikroklaselektroden abgeleitet. Der Muskel befindet sich in zwei durch eine Gummimembran getrennten Kompartimenten der Inkubationskammer, deren Potentiale von einem Spannungsgenerator kontrolliert werden. Bei Überschreiten eines Schwellen-Potentialgradienten kommt es zu repetitiver Reizbildung im Myokard. Der Schwellenwert nahm unter der Einwirkung von 100 µg/ml Tocainid von −285 mV auf −335 mV zu. Die Ergebnisse zeigen, daß sich Tocainid besonders zur Suppression von Arrhythmien eignet, die auf einer gesteigerten Automatie im Purkinjefasersystem beruhen.
Summary
The effect of tocainide on enhanced automaticity in Purkinje fibers was studied under the influence of epinephrine (0.2 µg/ml) by means of intracellular recordings with microglass electrodes. In the presence of tocainide 5 µg/ml and 10 µg/ml cycle length of enhanced automaticity was increased in the range of 10.6% and 34.9% and in the range of 26.3% and 108.7% respectively. Repetitive impulse formation in ventricular myocardium was generated by creating a potential difference in a papillary muscle mounted in a partition chamber. One chamber was connected to ground, the potential of the other chamber could be changed in the range of 0 to 500 mV. By progressively increasing the voltage difference across the papillary muscle repetitive rhythmic impulse formation was induced. The threshold voltage gradient increased in the presence of tocainide (100 µg/ml) from −285 to −335 mV. The results suggest that tocainide is suitable to suppress arrhythmias due to enhanced automaticity of Purkinje fibers.
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C. Naumann d'Alnoncourt was supported by a grant from the Deutsche Forschungsgemeinschaft and R. Cardinal by a Research Fellowship from the Canadian Heart Foundation
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Naumann d'Alnoncourt, C., Cardinal, R., Janse, M.J. et al. Effects of tocainide on ectopic impulse formation in isolated cardiac tissue. Klin Wochenschr 58, 227–231 (1980). https://doi.org/10.1007/BF01476968
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DOI: https://doi.org/10.1007/BF01476968