[Effect of motor activity on the development of arrhythmia in experimental emotional stress]. / Vliianie dvigatel'noi aktivnosti na vozniknovlenie serdechnykh aritmii pri eksperimental'nom émotsional'nom stresse.

Studies on monkeys and rabbits have shown that the experimental emotional stress can produce various disorders of cardiac rhythm: sinus tachycardia, atrial fibrillation, ventricular extrasystoles and paroxysmal ventricular tachysystoles. In these conditions the adrenaline content in the blood and myocardium is increased 3-4 times, the noradrenaline level is raised in the blood and decreased in the myocardium. Moderate motor activity leads to a relative decrease of adrenaline in the myocardium and arrest of cardiac arrhythmias. Marked motor activity on the contrary leads to an increase of the adrenaline and noradrenaline level in the myocardium and to the development of disorders of cardiac rhythm even up to ventricular fibrillation.

[Disorders in automatism and atrioventricular conduction during Luciani periods]. / Narusheniia avtomatii i atrioventrikuliarnogo provedeniia pri periodakh Liuchiani.

In isolated perfused hearts of rabbits and in spontaneously active preparations of the Purkinje fibers, conditions for occurrence of Luciani's periods were studied. Hypoxia, inhibitors of energy metabolism, inhibitor of the membrane Na+, K+ - ATPase ouabain, and acetylcholin were shown to induce primarily disturbances of the intracardiac conduction up to complete atrioventricular blockade in isolated hearts, periodic asystolia of ventricles occurring under these conditions only. With the aid of microelectrode recording of transmembrane potentials, Luciani's periods were found to be a periodic suppression of the Purkinje fibers' automatism. As distinct from the ventricles, no Luciani's periods occur in atria which indicates functional stability of the nomotopic pace-maker of the heart: the sino-atrial node.

[Effect of sulfhydryl compounds on the automatism of the pacemakers]. / Vliianie sul'fgidril'nykh grupp na avtomatiiu voditelei ritma serdtsa.

Experiments were performed on the isolated rabbit hearts and also on the hearts with complete atrioventricular block; a study was made of the effect of an excess or deficiency of the sulfhydryl groups on the automatism of the cardiac pace makers. Unithiol and cysteine in concentrations of 1-10(-6)-1-10(-4) g/ml were used as donors of sulfhydryl groups; deficiency of these groups was induced by the alloxan administration in concentrations of 1-10(-5)-5-10(-5) g/ml. Changes in the sulfhydryl group content produced no marked effect on the automatism of the synoatrial node. An excess of sulfhydryl groups promoted poststimulation depression of the automatism of the potential pace makers of the cardiac ventricles and could lead to the origination of Luciani's periods. On the contrary, in case of a deficiency of the sulfhydryl groups there was a sharp elevation of the automatism of the ventricular pace makers, the atrioventricular conduction became disturbed, and the poststimulation depression of the automatism became considerably diminished. Disturbances of the cardiac activity caused by the sulfhydryl group deficiency were completely eliminated by unithiol or cysteine.

[Effect of chronic stimulation of the negative and positive emotionogenic centers of the hypothalamus on development of cardiac arrhythmias]. / Vliianie khronicheskogo razdrazheniia otritsatel'nykh i polozhitel'nykh émotsiogennykh tsentrov gipotalamusa na vozniknovenie serdechnykh aritmii

Chronic experiments were conducted on 46 rabbits; a study was made of the changes in cardiac activity arising in prolonged (up to 1--2 weeks) electric stimulation of the ventro-median nuclei of the hypothalamus. Disturbances of the cardiac rhythm in the form of tachycardia, atrial flutter and fibrillation, ventricular extrasystole and paroxysmal ventricular tachysystole occurred mostly during the first days of stimulation and ceased after inderal infusion. Functional "weakness" of the cardiac pacemakers was revealed in the animals subjected to 1--2-week stimulation of the ventromedian nuclei. This was indicated by the post-stimulation suppression of the pacemaker automaticity and the appearance of Liciani's periods. Disturbances of the cardiac rhythm originating in stimulation of the ventromedian nuclei ceased in stimulation of the lateral hypothalamic field.

[Origin of Luciani periods during the effects of acetylcholine and eserine on the automation of Purkinje fibers]. / Vozniknovenie periodov Liuchiani pri deistvii atsetilkholina i ézerina na avtomatiiu volokon Purkin'e

Experiments were conducted on the isolated rabbit hearts with a complete atrio-ventricular block. It was shown that under the effect of acetylcholine (1.10(-7)-2.10(-6)g/ml) or eserine (1.10(-7)-2.10(-6)g/ml) there can occur Luciani periods which disappeared under the action of atropine (1.10(-6)g/ml). With the aid of microelectrodes it was revealed that Luciani periods appearing under the effect of acetylcholine or eserine were caused by periodic depression of automation of the Purkinje's fibers. This automation depression is regarded to be the result of a relative insufficiency of the active ionic transport processes.