[Analysis of ECG in ventricular fibrillation in man and animals based on chaos theory]. / Analiz EKG pri fibrilliatsii zheludochkov u cheloveka i zhivotnykh na osnove teorii khaosa.

The methods of the chaos theory were used to estimate the degree of irregularity of ventricular fibrillation in human and experimental animals. To verify the hypothesis that the degree of chaos depends on the species of the living organisms, the parameters characterizing the degrees of irregularity of ventricular fibrillation were estimated and compared. The comparative analysis was performed using 32 fragments of electrocardiographic records from five patients with sudden ventricular fibrillation bouts and 215 episodes of induced fibrillation in 17 animals. It was shown that fibrillation in human and animals has a different degree of regularity and different values of the chaotic component. The highest values of chaos were recorded in dogs, the lowest degree of chaos was observed in human. Rabbits and rats are intermediate, between dogs and humans. The fractuality of the structure-function organization of myocardium is discussed.

[Effect of emotional stress on the cardiac rhythm variability in rats]. / Vliianie émotsional'nogo stressa na variabel'nost' serdechnogo ritma u krys.

A degree of irregularities of the heart rhythm was studied by two methods: chaos-analysis and the HRV (heart rate variability) analysis. Our study shows an individual response in 3 groups of animals: 1--animals with low initial level of chaos (correlation dimension (PD2 < 2); 2--animals with high level of chaos (PD2 > 4); and animals with middle level of chaos (2 < PD2 < 4). The first two groups proved to be more sensitive to stress than the third group. Moreover we found that the electrical stability of the heart as measured by the fibrillation threshold, was higher for the chaos third group. The animals of the first two groups had low cardiac stability and high risk of stress-induced cardiac disturbances.

[Nitrogen monoxide in the mechanisms of cardiovascular functional resistance to emotional stress]. / Monooksid azota v mekhanizmakh ustoichivosti serdechno-sosudistykh funktsii pri émotsional'nom stresse.

The paper presents the results of examination of the mechanisms of development of different physiological dysfunctions (diminished cardiac electrical stability, fibrillation threshold fall) under emotional stress. Search was made for their drug correction (nitric oxide precursor L-arginine, the NO synthase blocker Ng-methyl-L-arginine and sodium nitrate). Experiments have indicated that L-arginine and sodium nitrate restore cardiac electrical stability. The normalizing effects of NO donors depended on the stage of cardiac disorders.

[Atrial fibrillation as the nonstationary process: analysis of chaotic dynamics]. / Fibrilliatsiia zheludochkov kak nestatsionarnyi protsess: metod analiza khaoticheskoi dinamiki.

A method for the mathematical analysis of recordings of the myocardium electrical activity during ventricular fibrillation is proposed. The method is based on evaluating the indices of the orderliness of the process. The entropy was one of the indices used. The analysis of EGG during ventricular fibrillation (an acute experiment on rats) revealed certain regularities in the apparently chaotic process of fibrillar oscillations. The entropy increased at the first stages of the fibrillation and then reached its maximal level. A gradual decrease in the entropy level preceded the spontaneous termination of fibrillation. This indicates that different stages of the process the degree of its disorganization changes. Upon spontaneous termination of fibrillation, quantitative changes transfer to qualitative changes. This reflects the transition of the myocardial system to another level of structural and functional organization.

[The effect of the combined action of chronic gamma irradiation and emotional stress in rats]. / Effekty kombinirovannogo deistviia khronicheskogo gamma-oblucheniia i émotsional'nogo stressa u krys.

Combined gamma irradiation and stress increased the emotional response in rats. The number of lymphoid cells increased significantly in the bone marrow, thymus and spleen, whereas fewer reticulocytes, neutrophils and thrombocytes were found in the peripheral blood.

Corticotropin-releasing factor induces differential behavioral and cardiovascular effects after intracerebroventricular and lateral hypothalamic/perifornical injections in rats.

The contribution of the lateral hypothalamic/perifornical (LH/PFx) area in mediating central effects of corticotropin-releasing factor (CRF) on cardiovascular and behavioral activity was assessed by monitoring blood pressure, heart rate and behavioral responses for a 45-min period after injections of various doses of CRF into the LH/PFx region or the lateral cerebral ventricle (intracerebroventricular, i.c.v.) in conscious, unrestrained rats in a familiar environment. After LH/PFx injection, CRF (3 and 30 ng) dose-dependently induced behavioral activation, predominantly consisting of grooming, eating and locomotor activity. Concomitantly, dose-related increases in mean arterial pressure (delta MAP) and heart rate (delta HR) were observed. Increases in MAP and HR following injection of 3 ng CRF were associated with the paroxysmal occurrence of behavioral activation and as such superimposed on CRF-induced elevation of baseline MAP and HR. Thirty nanograms CRF given i.c.v. produced grooming behavior similar to that observed after the same dose injected into the LH/PFx region, but failed to induce significant changes in cardiovascular concomitants. Rats receiving 100 ng CRF i.c.v., showed a significant increase in behavioral activity, respective to rats treated with 30 ng CRF in the LH/PFx, the tachycardiac responses, however, being similar in these groups. Both doses of CRF i.c.v. failed to induce significant delta MAP. The effects of CRF on cardiovascular and behavioral activity were more marked when the peptide was injected into the caudal part of the LH than those measured after administration into the rostral LH. Similarly, injections of CRF around or dorsal to the fornix (PFx) were more effective than those located ventrally to it. This site specificity of CRF-evoked responses was reflected in differential time response relations of the various effects. In summary, when i.c.v. is the route of administration, a higher dose of CRF is required to induce autonomic and behavioral responses similar to those elicited by CRF injected into the LH/PFx. The cardiovascular and behavioral effects of LH/PFx-CRF indicate that this region may be an important site for central CRF to produce stress-related autonomic and behavioral responses. In addition, the CRF-induced effects, both in magnitude and onset, show site specificity, the caudal LH and perifornical area being more responsive to the peptide than the rostral LH and the area ventral to the Fx. As CRF-evoked behavioral activation does not necessarily coincide with changes in MAP and HR, our data suggest a dissociation of the peptide's central actions to influence behavioral and autonomic responses.

[Blood catecholamine levels in rabbits with varying resistance of the cardiovascular system to emotional stress]. / Kontsentratsiia katekholaminov v krovi krolikov s raznoi ustoichivost'iu serdechno-sosudistoi sistemy k émotsional'nomu stressu.

The content of catecholamines and some products of their metabolism in the blood of rabbits with different resistance of the cardiovascular system to acute emotional stress was determined by high performance liquid chromatography with electrochemical detection. It was shown that in rabbits with mild arterial pressure (AP) changes in noradrenaline (NA) concentration increased by 145% by the end of the 3rd hour of the experiment. In rabbits with progressively reducing AP the blood NA concentration increased (by 272%) 10 minutes after the beginning of stimulation of the ventromedial nuclei of the hypothalamus and remained increased (to 500%) to the end of the experiment. The concentration of adrenaline and 3-4 dioxyphenylacetic acid was also increased in these animals.

[Biogenic amines in the ganglia of the autonomic nervous system in emotional stress]. / Biogennye aminy v gangliiakh avtonomnoi nervnoi sistemy pri émotsional'nom stresse.

Rabbits with different stability of cardiovascular functions were shown to have different activity of sympathetic nervous system under emotional stress. A small enhancement of the system activity occurred in animals with practically unchanged arterial pressure, whereas its hyperactivity was found in the animals with a progressive decrease of arterial pressure. Different changes of catecholamines in the nodose ganglia of these two groups of animals seem to reflect the participation of those ganglia in the maintenance of stable cardiovascular functions in extreme conditions.

[Angiotensin II in the mechanisms of hypothalamic pressor reactions]. / Angiotenzin II v mekhanizmakh pressornykh gipotalamicheskikh reaktsii.

The influence of intracerebroventricular injections of the angiotensin II antagonist--saralasin on the cardiovascular reactions elicited by electrical stimulation of different structures of the hypothalamus in rabbit was studied. The saralasin in doses from 1 to 1.5 mg reduced arterial pressure by 9 +/- 0.2 mm Hg and decreased the amplitude of the hypertensive reactions elicited by electrical stimulation of the paraventricular, supraoptic, ventromedial, supramammillary nucleus of the hypothalamus, area hypothalamic anterior and lateral. It has been shown that most suppressing influence of the saralasin on amplitude of the hypertensive reactions elicited by electrical stimulation of the paraventricular (68%) and supraoptic (76%) nucleus of the hypothalamus which contain magnocellular neurosecretory neurons.

[Electroencephalographic analysis of inter-central relations in hypothalamo-reticulo-limbic brain structures during treatment with corticosteroids and neuropeptides]. / Elektroéntsefalograficheskii analiz mezhtsentral'nykh vzaimootnoshenii gipotalamoretikulolimbicheskikh struktur mozga pri deistvii kortikosteroidov i neiropeptidov.

Intercentral relations between hypothalamus, limbic system and reticular formation were studied in rabbits and rats under systemic and central action of DSIP, ACTH, corticosteroids and stress (aggressive-defensive behaviour). The results obtained demonstrate changes in the adrenal cortex resulting from stress-inducing adrenocortical hormone content. The increase was achieved by the rise in ACTH level resulting in corticosteroid level elevation (endogenous elevation-aggressive behaviour) and by corticosteroid injections (exogenous elevation). Correlation analysis of structural interrelations after ACTH and corticosteroid injections demonstrated an increased correlation between hypothalamo-reticular-limbic structures. DSIP was shown to have an opposite effect. Correlation analysis revealed the potentials for the formation of new functional interrelations between hypothalamo-reticular-limbic structure in the motivation of aggression (stress) and the levels of corticosterone and DSIP. DSIP action depends on the initial corticosteroid blood level and is more marked in stress-inducing concentrations.

[Comparative analysis of changes in intercentral relations of the brain as a result of administration of delta-sleep peptide and ACTH]. / Sravnitel'nyi analiz izmenenii mezhtsentral'nykh vzaimootnoshenii mozga pri deistvii peptida delta-sna i AKTG.

Elucidation of the mechanisms of the DSIP effect on the CNS functional state is one of the leading problems of neuroendocrinology. The investigation of DSIP physiological properties as antistress factor in systemic mechanisms of emotional stress is of great interest. The purpose of our studies was to investigate the character of changes in intercentral interrelationships among hypothalamus, limbic system and reticular formation in augmentation of corticosteroids level up to the stressful one. We also studied the character of changes in intercentral interrelationship under the DSIP effect. The latter depends on the initial level of corticosteroids in the blood and is more obvious at the stress level. DSIP, ACTH and steroid hormones facilitate the process of the self-organization of the brain as well as the formation of the current behavioral responses.

[Acetylcholinesterase and choline acetyltransferase in the nervous system of rabbits predisposed to cardiovascular disorders under emotional stress]. / Atsetilkholinésteraza i kholinatsetiltransferaza v nervnoi sisteme krolikov, predraspolozhennykh k narusheniiu serdechno-sosudistykh funktsii pri émotsional'nom stresse.

A study was made of the activity of acetylcholinesterase (AChE), cholinacetyl transferase (CAT), butyril cholinesterase (BCE) and water-soluble proteins in the structures of the CNS and in the autonomous ganglia in rabbits predisposed to cardiovascular disorders under emotional stress. It was established that unlike resistant animals, in those predisposed to cardiovascular disorders, the CAT content in the periphornical area of the hypothalamus did not differ from the control, the content of water-soluble proteins in the CNS structures and the ganglia remained unchanged either as compared with the control. The authors assume that the data obtained confirm a previously advanced concept of the involvement of the cholinergic system of the periphornical area of the hypothalamus in the maintenance of the stability of cardiovascular functions by regulation of the water-salt metabolism.

[Monoamine oxidase activity in rabbit brain nuclei in experimental acute emotional stress]. / Aktivnost' monoaminoksidazy v iadrakh mozga krolika v usloviiakh ostrogo éksperimental'nogo émotsional'nogo stressa.

Activity of monoamine oxidase in the neurons of catecholamine-synthesizing nuclei of hypothalamic and brainstem of rabbits with different resistance of cardiovascular functions to emotional stress was studied by the Glenner et al. method. An acute experimental emotional stress was induced by non-periodic electric stimulation of the hypothalamic ventromedial nucleus and the skin in immobilized adult chinchilla rabbits. It was found that monoamine oxidase activity in the neurons of groups A5, A6, A7 and A14 under acute experimental emotional stress increased in rabbits "resistant"to stress and remained unchanged in rabbits "predisposed" to stress. The activity of monoamine oxidase in the neurons of group A12 remained unchanged in the rabbits "resistant"to stress and decreased in the rabbit "predisposed" to stress.

[Monoamine oxidase activity in autonomic ganglia of rabbits with differing resistance of cardiovascular functions to emotional stress]. / Aktivnost' monoaminoksidazy v gangliiakh vegetativnoi nervnoi sistemy krolikov s raznoi ustoichivost'iu serdechno-sosudistykh funktsii k émotsional'nomu stressu.

The Glenner method was used to study monoamine oxidase (MAO) activity in the neurons of superior cervical, stellatum and nodosum ganglia of rabbits with different resistance of cardiovascular functions to emotional stress. Acute experimental emotional stress was induced by electrical stimulation of the hypothalamus and skin in immobilized adult male Chinchilla rabbits. MAO activity was found to be changed in the neurons of sympathetic ganglia (cervical and stellatum) under acute experimental emotional stress. In stress-resistant rabbits, MAO activity increased, while in stress-predisposed animals, it declined. MAO activity in the nodose ganglion of the vagus nerve remained unchanged under acute experimental emotional stress.

[Acetylcholinesterase and choline acetyltransferase in the nervous system of rabbits resistant to emotional stress]. / Atsetilkholinesteraza i kholinatsetiltransferaza v nervnoi sisteme krolikov, ustoichivykh k émotsional'nomu stressu.

To study the role of acetylcholine metabolism system in the mechanisms responsible for animals' resistance to emotional stress, the activity of acetylcholinesterase (AChE), butyrylcholinesterase and cholinacetyltransferase (CAT) was evaluated in brain structures and autonomous vegetative nervous system of rabbits after experimental emotional stress. In the course of experiments, arterial pressure and heart rate were recorded. The rabbits whose cardiovascular functions appeared to be resistant showed an increase in the activity of AChE and CAT in the perifocal area of the hypothalamus. It is suggested that the involvement of the perifocal area of the hypothalamus in the formation of the mechanisms responsible for the resistance is linked with the effects on water-salt metabolism.

[Influence of renin on the effects of electric stimulation on the ventromedial hypothalamus]. / Vliianie renina na éffekty élektricheskoi stimuliatsii ventromedial'nogo gipotalamusa.

The influence of intraventricular injection of different doses of renin on the effects of electrical stimulation of the ventromedial hypothalamus was studied. Injection of renin (10 micrograms/kg) into the lateral ventricles of the brain of experimental animals elicited a prolonged elevation of arterial pressure and a decrease of the heart rate, while given in doses of 20 and 30 micrograms/kg it also provoked arrhythmias and ventricular extrasystoles, and a lowering of the threshold of ventromedial hypothalamus stimulation. It was found that under the central action of renin, a short-term stimulation of the ventromedial hypothalamus provoked ventricular extrasystoles.

[Acute emotional stress and cyclic nucleotide content of the heart and blood plasma]. / Ostryi émotsional'nyi stress i soderzhanie tsiklicheskikh nukleotidov v serdtse i plazme krovi.

The relationships between the changes in arterial pressure and the content of cyclic nucleotides in the heart and blood plasma were studied on rabbits exposed to acute emotional stress. During 3 hours of the stress program, there were changes in arterial pressure, namely an elevation within the first hour followed by a progressive fall during subsequent 2 hours and death of the animals. The content of cAMP in the heart rose to a greater degree than that of cGMP. The content of cAMP in the blood plasma considerably increased, while the level of cGMP remained unchanged. The data obtained attest to the predominance of activation of adrenergic structures over activation of cholinergic structures.

[Tyrosine hydroxylase activity in rabbit autonomic nervous system ganglia in acute experimental emotional stress]. / Aktivnost'tirozingidroksilazy v uzlakh vegetativnoi nervnoi sistemy krolikov pri ostrom éksperimental'nom émotsional'nom stresse.

The Zigmond method was made use of to study tyrosine hydroxylase activity in cervical, stellate and nodosal ganglia of rabbits predisposed and resistant to stress. Experimental acute emotional stress was induced by concurrent stimulation of the ventromedial nuclei of the hypothalamus and different skin areas. Experiments have shown that changes in metabolic activity of the sympathetic and parasympathetic systems were phasic in nature throughout 3 hours of the experiment. The changes in tyrosine hydroxylase activity in nodosal and stellate ganglia of rabbits predisposed to stress differs from those in stress-resistant animals. Stress-predisposed rabbits manifested a decrease in the activity of tyrosine hydroxylase in stellate and nodosal ganglia.