On mechanism of antiarrhythmic action of some dimethylphenylacetamide derivatives

Abbreviations: AC – acetylcholyne; AF – atrial fibrillation; AP – action potential; BLM – bi-lipid membrane; DPA – Dimethylphenylacetamide; VA – ventricular arrhythmia Introduction: The study aim was to identify essential elements of the antiarrhythmic action mechanism of tertiary and quaternary derivatives of Dimethylphenylacetamide. Materials and Methods: The study was conducted in albino rats and mice of both sexes; isolated neurons of mollusc Limneastagnalis; and strips of rats’ right ventricle myocardium. Two compounds of Dimethylphenylacetamide LKhT-3-00 and LKhT-12-02 were studied. The cholynolytic property of the compounds was investigated by using a Schallek method in the authors’ modification. The adrenotropic activity of the derivatives was explored by Moore and Spear (1984), as well a by the method of catecholamine level detection in heart tissue. The permeability of derivatives through BLM was evaluated experimentally and theoretically. The derivatives’ influence on Na+-current was studied directly and indirectly. Results and Discussion: Neither tertiary nor quaternary derivatives possess the cholynolytic property. LKhT-3-00 prevented an increase in the adrenaline concentration in the left ventricle myocardium. The compounds prevent catecholamine arrhythmia and conductivity disorders. LKhT-3-00 like Lidocaine passes through the BLM of the cardiac cell in an ionised form, whereas the quaternary derivative permeates cardiac cell membrane in an electro-neutral form. Lidocaine derivatives restrain acute ischemia-induced oxidative process growth in the cardiac muscle. Simultaneously, the LKhT-3-00 compound can activate antioxidant mechanisms and prevent acidosis and optimise the balance between [O2] and [CO2] concentrations in coronary dark blood. At a concentration of 10 mg/ml, although the derivatives reduce the amplitude of the leading edge of AP and its rate of increase, they do not, however, affect the duration of AP. Conclusions: The compounds possess the Na+-blocking and cell-protecting properties. They do not affect K+-current through Kv4.3-channels.