Electrophysiological effects of diclofurime on rabbit and frog atrial heart muscle

1 The effects of diclofurime on the electrical activity of the rabbit sinus node, rabbit atria and frog atrial fibres were studied using microelectrode and the double sucrose gap voltage‐clamp techniques respectively. 2 In rabbit sinus node, diclofurime (10−7 m to 10−6 m) decreased the action potent...

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Bibliographic Details
Published in:British journal of pharmacology 1987-04, Vol.90 (4), p.717-725
Main Authors: Gautier, Patrick, Guiraudou, Pierre, Sauviat, Martin‐Pierre
Format: Article
Language:English
Subjects:
Action Potentials - drug effects
Animals
Biological and medical sciences
Cardiovascular system
Dose-Response Relationship, Drug
Female
Heart - drug effects
Heart - physiology
In Vitro Techniques
Male
Medical sciences
Oximes - pharmacology
Pharmacology. Drug treatments
Rabbits
Sodium - metabolism
Vasodilator Agents - pharmacology
Vasodilator agents. Cerebral vasodilators
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Summary:1 The effects of diclofurime on the electrical activity of the rabbit sinus node, rabbit atria and frog atrial fibres were studied using microelectrode and the double sucrose gap voltage‐clamp techniques respectively. 2 In rabbit sinus node, diclofurime (10−7 m to 10−6 m) decreased the action potential (AP) amplitude and maximum rate of depolarization , increased the AP duration and slowed the sinus rate. 3 In rabbit atria, the drug reduced the amplitude of the depolarizing phase and , lengthened the AP duration and decreased the resting membrane potential. 4 In frog atrial fibres, the drug (10−5 m) depolarized the resting membrane potential, decreased as well as the plateau amplitude. It inhibited the sodium current (INa) with a dissociation constant of 3.7 × 10−6 M and a one to one relationship between the drug molecule and the Na channel. Diclofurime did not alter the apparent reversal potential for the fast Na current (ENa) but it inhibited the sodium conductance (GNa) in a frequency‐dependent manner. 5 Diclofurime also blocked the slow inward current (Islow) without alteration of Eslow. The block of Islow occurred with a dissociation constant of 2 × 10−5 m and unity stoichiometry. 6 The data suggest that diclofurime might be effective in the control of cardiac arrythmias since it exhibited both local anaesthetic‐like and calcium antagonistic properties.
ISSN:0007-1188
1476-5381
DOI:10.1111/j.1476-5381.1987.tb11225.x