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The antiarrhythmic effect of potassium and rubidium in strophanthidin toxicity
Abstract:
The effect of potassium and rubidium on the electrical and mechanical activity of canine Purkinje fibers were studied in vitro in the presence and absence of strophanthidin. High (5.4mM) K or 2.7 Rb decreased the force of contraction. In the presence of these ions, strophanthidin increased the force of contraction as usual but the onset of arrhythmias was delayed. During the toxic stage of strophanthidin, high K or Rb increased the force of contraction, abolished the arrhythias and improved markedly the action potential. In the presence of calcium overload induced by exposure to a K-poor or Na-free solution, K and Rb induced an increase in force of contraction. And in ventricular muscle these ions relaxed the contracture induced by strophanthidin. It is concluded that K and Rb (in addition to other mechanisms) exert an antiarrhythmic action by increasing potassium conductance and by reducing the calcium overload induced by strophanthidin.
Insights
Potassium (K) and rubidium (Rb) ions can mitigate strophanthidin-induced cardiac arrhythmias and improve electrical activity. These ions reduce calcium overload, offering a potential antiarrhythmic mechanism in heart muscle.
Area of Science:
- Cardiovascular Physiology
- Electrophysiology
- Pharmacology
Background:
- Strophanthidin is a cardiac glycoside known to induce arrhythmias.
- The role of potassium and rubidium in modulating cardiac activity during strophanthidin toxicity is not fully understood.
Purpose of the Study:
- To investigate the effects of potassium (K) and rubidium (Rb) on the electrical and mechanical activity of canine Purkinje fibers in the presence and absence of strophanthidin.
- To elucidate the antiarrhythmic mechanisms of K and Rb during strophanthidin toxicity and calcium overload.
Main Methods:
- In vitro study using canine Purkinje fibers.
- Administration of varying concentrations of K and Rb.
- Exposure to strophanthidin and induction of calcium overload using K-poor or Na-free solutions.
Main Results:
- High concentrations of K or Rb decreased the initial force of contraction.
- In the presence of strophanthidin, K and Rb delayed the onset of arrhythmias and improved action potentials during toxicity.
- K and Rb increased the force of contraction during strophanthidin toxicity and relaxed strophanthidin-induced contracture in ventricular muscle.
- These ions increased contraction force in the presence of calcium overload.
Conclusions:
- Potassium and rubidium exert antiarrhythmic effects by increasing potassium conductance.
- These ions reduce strophanthidin-induced calcium overload, contributing to their protective action.
- K and Rb demonstrate potential as therapeutic agents for managing cardiac glycoside toxicity.