Key result
16-epi-gitoxin prolongs Purkinje fibre survival ~2.5 times vs ouabain with reversible effects on inexcitability.
Why the study?
Does 16-epi-gitoxin have different toxic effects compared to ouabain on isolated canine Purkinje and ventricular muscle fibres?
Does 16-epi-gitoxin have different toxic effects compared to ouabain on isolated canine Purkinje and ventricular muscle fibres?
The semisynthetic glycoside 16-epi-gitoxin exerts a weaker and more reversible toxic effect on the specialized conducting system compared to ouabain in canine cardiac fibres.
Does not support clinical use; leaves open whether 16-epi-gitoxin offers safer conduction effects than ouabain in humans.
Action potentials of isolated Purkinje fibres and ventricular muscle fibres of canine hearts treated with ouabain and 16-epi-gitoxin were recorded by microelectrodes. Under the influence of both glycosides, Purkinje system fibres became inexcitable earlier than ventricular muscle fibres. Being exposed to 0.125 muM ouabain and 2.5 muM 16-epi-gitoxin, both Purkinje and ventricular muscle fibres became poisoned in the same time as ventricular muscle fibres exposed to 0.1 muM ouabain and 1.5 muM 16-epi-gitoxin. At the lower 16-epi-gitoxin concentration Purkinje fibres had 2.5 times the survival time of that exposed to the lower ouabain concentration. Compared to 16-epi-gitoxin the inexcitability of Purkinje fibres after ouabain remained irreversible. The semisynthetic glycoside 16-epi-gitoxin exerts a weaker effect on the specialized conducting system.
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Knut-Olaf Haustein (2008) studied this question. 16-epi-gitoxin vs. Ouabain was evaluated on Survival time and inexcitability of Purkinje and ventricular muscle fibres. 16-epi-gitoxin resulted in a 2.5 times longer survival time for Purkinje fibres compared to ouabain at lower concentrations, and its effects on inexcitability were reversible.
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