Neurohistochemical and electron microscopic investigations of pathological and age-related changes in the cardiovascular system.

Neurohistochemical and electron microscopic investigations of the autonomic nervous system (ANS) of man and animals suggest that its ontogenesis can be divided into the premediatory, mediatory and postmediatory periods of development. The postmediatory period begins heterochronically in various ganglia of the ANS. A normal process of early cardiac desympathization usually occurs at the age of 35 to 60 years. Specific changes of preceding sudden cardiac death are elicited in different parts of the ANS and adrenal glands. This is accompanied by focal myocardial desympathization. Coronary vessels and conducting system which may influence myocardial hypersensitivity zones to catecholamines are involved in the process of destabilization of the cardiac function. Moreover, relationships are demonstrated which exist between the atherosclerotic lesions of the aortic wall and the status of its nerve plexuses.

[The effect of taurine on the density of adrenergic nerve endings and the recovery of cardiac function after ischemia]. / Vliianie taurina na plotnost' adrenergicheskikh nervnykh okonchanii i vosstanovlenie funktsii serdtsa posle ishemii.

Isolated guinea-pig hearts perfused at 37 degrees C with Krebs-Henseleit buffer through aorta. Mechanical function was evaluated by isovolumic pressure in a latex balloon inserted into left ventricle. The density of catecholamine-containing adrenergic nerve plexus was measured in both ventricles after 40 min of total ischemia and 30 min of reperfusion. Heart preparations were treated with 2% glyoxylic acid and the relative area occupied by the plexus was determined alanimetrically. Without taurine (control) the adrenergic plexus density was 4-(right ventricule) and 6-fold (left ventricule) lower compared with that in freshly isolated hearts. When taurine was added to the perfusion solution after ischemia, the plexus density increased about 2.7-fold; if it was added prior to ischemia, the density was nearly equal to the original value. In no experiment with taurine addition during reperfusion fibrillation did occur, and about 2-fold more rapid restoration of regular rhythm was observed comparing with the control and experiments when taurine was added prior to ischemia. Both in the latter and control experiments spontaneously disappearing fibrillation occurred. The restoration of pressure and contraction frequency were virtually the same in all experiments. These findings show that taurine is able to preserve the catecholamine stores in the myocardium.

[Coronary chemoreceptors in rabbits]. / Koronarnyi khemoretseptor u krolika.

Position and structure of the coronary ++chemoreceptor (CH) have been studied in 40 Chinchilla rabbits by means of neurohistological and histochemical methods. The CH is situated in the adventitia of the left coronary artery. The CH together with chromaffin cells includes blood vessels, small nervous fasciculi and connective tissue. According to luminescent intensity 2 groups of cells are distinguished. Two types of CH cells are revealed morphometrically, they differ in their size. Metachromasia at staining with toluidine++ blue demonstrates presence of serotonin in the CH. A possible role of the CH in pathogenesis of a sudden death is considered.

[Adrenergic innervation of various sections of the heart in laboratory animals and man]. / Adrenergicheskaia innervatsiia razlichnykh otdelov serdtsa u laboratornykh zhivotnykh i cheloveka.

By means of incubating slices in 2% glyoxylic acid solution, distribution of adrenergic fibers in the myocardium of various cardiac parts has been studied in the white rat, rabbit, cat, guinea pig and in the man. Both in the animals and in the man the distribution density of the adrenergic fibers of the myocardial plexuses in the auricle is higher than in the ventricle, and in the left half of the heart it is lower than in the right one. There are certain species differences in distribution of the adrenergic fibers. The density of the adrenergic fibers in the guinea pig myocardium is the highest, and in the white rat is is the lowest.

[Structure of the cholinergic nerve plexuses of the heart and their function in sudden cardiac death]. / Stroenie kholinergicheskikh nervnykh spletenii serdtsa i ikh sostoianie pri vnezapnoi serdechnoi smerti.

54 hearts of men aged 30-60 were studied histochemically. The control consisted of 12 hearts of persons who died of cerebral injury. 42 persons died suddenly by fresh myocardial infarction, small-focal cardiosclerosis, postinfarction cardiosclerosis or alcohol cardiomyopathy. The density of nervous plexus was higher in the right atrium than in the left one. Right and left ventricle differed in the same way. In older persons, especially those who died suddenly, density of myocardial cholinergic nervous plexus (especially perivasal) decreased which was associated with development of perivasal fibrosis characteristic for neurotomy of perivasal plexus. Density of cardiac cholinergic plexus differed in various myocardial pathologies. It was the highest in sudden death in patients with small-focal cardiosclerosis and the lowest in sudden death in patients with fresh myocardial infarction.

[The microcirculatory bed of the human myocardium in sudden cardiac death]. / Izuchenie mikrotsirkuliatornogo rusla miokarda cheloveka pri vnezapnoi serdechnoi smerti.

A ventricular capillary bed was studied in 30 hearts of humans upon sudden cardiac death according to modified technique of Karnovsky-Roots. A 10-80% narrowing of coronary artery lumen was found due to formation of atherosclerotic plaques. The assessment of butyrylcholinesterase activity in myocardial sections proved helpful in providing the appearance of microcirculation from small arterioles to venules. Determination of volumetric density of microvessels suggested an inverse correlation between the degree of stenosis of major coronary arterial branches and volumetric density of ventricular capillaries in the heart.

Changes in neural and humoral mechanisms of the heart in sudden death due to myocardial abnormalities.

Quantitative neurohistochemical study of adrenergic elements of the myocardium and the adrenal medulla in victims of sudden death revealed an unequal and focal depletion of catecholamines attributable to prior pathologic processes in the myocardium. The greatest changes in cardiac innervation were found in cases of acute myocardial infarction and alcoholic cardiomyopathy, and the adrenergic plexuses were better preserved in cases of coronary heart disease without focal myocardial changes. Ultrastructural study of cardiac innervation in patients who died suddenly showed more pronounced changes in the nerve plexuses of the sinus node than in the perinodal nerves of the working myocardium. The changes in coronary artery innervation were usually related to the severity of stenosis due to fibrous plaque; desympathization of the vessels and the adjoining myocardial zone was also found in cases with 50% or greater occlusion of the lumen. The bulk of chromaffinocytes were depleted and weakly luminescent in the adrenal glands of patients with acute myocardial infarction who died suddenly. In contrast, chromaffinocytes with moderate and bright luminescence were prevalent in cases of sudden death with scarring from previous myocardial infarction and with alcoholic cardiomyopathy. Ultrastructural and histochemical examinations demonstrated that changes in the neurons of sympathetic ganglia increased with more severe atherosclerotic lesions of the aorta and with greater changes in the vessels supplying the ganglia. In experiments on rabbits and dogs, both coronary artery ligation and electrostimulation produced cardiac fibrillation followed by a local increase in luminescence intensity of the myocardial nerve plexuses when their density remained high. Chemoreceptors located along the coronary vessels and pulmonary artery in dogs included small cells with bright fluorescence and adrenergic nerve fibers.

[Adrenergic innervation of the coronary arteries of the human heart and changes in it in atherosclerosis]. / Adrenergicheskaia innervatsiia koronarnykh arterii serdtsa cheloveka i ee izmeneniia pri ateroskleroze.

Luminescent histochemical studies of autopsy specimens (30 cases) representing various markedness of coronary arterial atherosclerosis (segments from the left circumflex and the left anterior interventricular coronary arteries) showed that various portions of the blood channel differed with respect to the density of adrenergic nerve plexuses depending on the extent of atherosclerotic vascular stenosis. Morphometrically, the density of adrenergic fibres in the superficial adventitial layers of the atherosclerotically-affected left circumflex artery was, on the average, 1.4 times, and that of the anterior interventricular artery, 1.8 times as low as the density at similar sites of unstenosed vessels. In deeper layers, the density of adrenergic plexuses in the affected segments of both arteries is reduced twofold, as compared to similar segments of unaffected arteries.

[Changes in the intracardiac nerve plexuses in sudden death]. / Izmeneniia vnutriserdechnykh nervnykh spletenii pri vnezapnoi smerti.

Neurohistoligical and histochemical study of 57 cases of sudden cardiac death and control material in the age aspect revealed deep changes in the intracardiac nerve plexuses. In cases of sudden cardiac death conjoint mosaic changes were seen in the microcirculation channel in which regions with empty capillaries and areas of blood stasis were found. In some of the cholinergic neurons signs of edema were seen and cholinesterase activity was reduced, though it was still high in the preterminal and terminal plexuses stretching along the conduction system and blood vessels and in the myocardium. The regional microcirculatory disorders may be linked with the neuroregulative metabolic disorders.

[Simple method of demonstrating adrenergic nerve structures in human and animal tissues using a glyoxylic acid solution]. / Prostoi sposob vyiavleniia adrenergicheskikh nervnykh struktur v tkaniakh cheloveka i zhivotnykh s primeneniem rastvora glioksilovoi kisloty.

A method for obtaining injection replications of microvessels for scanning electron microscopy using nonsaturated polyether resin PH-8 is described. Possible applications of the method in question to study microcirculatory bed are discussed. With resine PH-8 it is possible to obtain complete and detailed replications which give information on three-dimensional organization both of the microcirculatory bed and of the vascular microrelief peculiarities.