Gangliosides of the bovine heart impulse conducting system

The ganglioside analysis of the heart impulse conducting system was carried out, comparing it with that of ordinary myocardium. The heart impulse conducting system contained about 3-times more gangliosides than ordinary myocardium and showed a distinctly different ganglioside composition. These observations seemed to indicate that the differentiation between myoblasts and each type of cardiac muscle cell, impulse conducting system and ordinary myocardium cells, resulted in their characteristic ganglioside compositions.     

Types of anatomic correspondence between the conducting system and the heart

The principles of a quantitative determination of characteristics concerning the types of anatomical correspondence between the conduction system and the heart at its congenital malformations are presented. This makes it possible to establish that the topographoanatomical type of the conduction system depends on the peculiarities of the heart structure at its congenital malformations rather than from changes in the structure and position of the parts of the conduction system, or the conduction system as a whole according to the types of congenital heart malformations. The mechanism of the left-sided position of the atrioventricular bundle (His bundle) in some congenital malformations of the heart is explained.     

Electron microscopic study of the innervation of the heart conduction system in rats]

A systemic quantitative electron microscopic analysis on innervation of the sinus node, the atrioventricular node, the bundle of His and its pedicles within the interventricular septum has been performed in intact hearts of mature rats. The data have been obtained on the size of nonmyelinated and myelinated nerve fibres, efferent and afferent terminals within different parts of the cardiac conductive system, their interconnection with specialized cardiomyocytes have been described. Application of certain methods for electron microscopic investigation on the innervation of mammalian cardiac conductive system has been discussed.     

On the impulse conducting system of the monkey heart (Macaca mulatta)

Summary The atrio-ventricular (A-V) node of the monkey heart is located in the focus of converging atrial muscle. Three main atrial muscle strands, coming from the atrio-ventricular ring, the dorsal wall of the atria, and the ventral part of the atrial septum, converge in the nodal region where they overlap and are interconnected. The junctional type of fibers establishing interconnection between the atrial muscle and the nodal tissue are not strictly localized at the periphery of the node, but may be traced further, along the A-V ring and coronary sinus. The A-V node consists of a loose peripheral and a compact distal part. In the former, typical nodal fibers were found, while the compact part shows an important individual variation in structure and cell-types. In some monkey hearts, the nodal fibers gradually become broader bundle fibers, while in other specimens the junctional fibers surround the compact part and than penetrate the nodal-His (N-H) region. These junctional fibers become nodal fibers or are in terminal contact with large clear cells up to 50 in diameter. Clear cells of various diameters are often intercalated between the cell rows of the nodal and His-bundle fibers and may form a distinct cellular gate between the node and the His-bundle.This study was conducted in part in the Department of Histology and Embryology of the Medical University in Budapest.     

Morphology of the microtubule system in mouse kidney epithelial cells]

The cultured mouse kidney cells forming epithelial sheets were studied using an indirect immunofluorescence microscopy with antibodies against tubulin. These cells, as well as fibroblasts, were found to contain a well developed microtubular system sensitive to colcemid. The assembly of microtubules after washing out of colcemid began from one or two perinuclear centers, associated with the cilium-like structure. There were certain differences between the microtubular systems in epithelial cells and fibroblasts: 1) Microtubules in the fibroblasts penetrated the whole cytoplasm including the peripheral lamella whereas in the epithelial cells the lamellar cytoplasm was often free from microtubules. 2) The orientation of microtubules in the epithelial cells, unlike in the fibroblasts, was not correlated with the stable or active state of the cell margin. A possible role of microtubular system in the epithelial cells and fibroblasts is compared and discussed.     

The fine structure of the conducting system of the monkey heart (Macaca mulatta)

Summary In the sino-atrial (S-A) node of the monkey heart two types of muscle cells occur: 1. typical nodal cells which are the predominant cells and form the nodal fibers. 2. Intercalated clear cells with various diameters (4 to 12 m) and containing poorly developed myofibrils, rich in glycogen and demonstrating poor staining properties. These latter cells are dispersed, few in number, and never form discrete fibers of themselves, but are intercalated between the cell rows of the typical nodal fibers. Such intercalated clear cells become more numerous at the periphery of the node. Interconnection between the S-A node and the conventional atrial muscle is established by a progressive transformation of nodal fibers into atrial fibers producing an intermediate (or junctional) type of fiber at the nodal periphery. However, in addition, few nodal fibers make direct contact with the atrial cardiocytes. Our light and EM studies have failed to prove the existence of truly specialized internodal pathways. Nevertheless intercalated clear cells, nodal-like cells, junctional or intermediate type of cells are relatively frequent in valvular regions (Thebesian, Eustachian, A-V, fossa ovalis) and less frequent in other regions of the atrial wall.This study was conducted in part in the Department of Histology and Embryology of the Medical University in Budapest.     

Effect of cimetidine on the heart conduction system]

An effect of cimetidine on ECG records has been investigated in a group of 40 patients with gastric or duodenal ulcers and coexisting circulatory disorders. For this purpose ECG has been recorded with Holter's technique (Medilog 2000) together with ECG-recording using high amplifying technique. An intravenous injection of 200 mg of cimetidine produced in some of patients inhibition of the sinus rhythm atrio-ventricular conduction disturbances as well as changes in the end phase of ECG ventricular image. The authors suggest, that intravenous administration of cimetidine to patients with cardiac diseases should be monitored with ECG recording.     

Reflex actions of the functional divisions in the crayfish oculomotor system

Summary The electrical responses of motor neurons in different anatomical subdivisions of the crayfish oculomotor system were examined during various kinds of experimentally manipulated sensory stimulation. Geotactic reflexes are effected by neurons in the anterior motor cluster and the medulla terminalis. Optokinetic and proprioceptive nystagmus are generated by neurons in the lateral motor cluster. This functional diversity in the major subdivisions contrasts with an intradivisional homogeneity of function, in that the different motor neurons of each all contribute to reflexes initiated by different kinds of sensory input.This research was supported by USPHS Research Grant NS 04989.     

Corticalization of two divisions of the visual system during vertebrate evolution

Data on the evolution of the visual system in vertebrate phylogeny are described. Visual projections are demonstrated in the telencephalon of cyclostomata (lampreys). The existence of a retino-thalamo-telencephalic pathway is demonstrated in elasmobranchs (skates). Two visual pathways are present in amphibians (frogs) and reptiles (turtles): retino-thalamo-telencephalic and retino-tecto-thalamo-telencephalic, and these overlap partly at the thalamic level in the lateral geniculate nucleus and completely in the telencephalon. In turtles the earliest visual and tectal impulses relay on their way to the telencephalon in the lateral geniculate body, and later impulses relay in the nucleus rotundus. In mammals (rats) visual tecto-cortical connections are seen; judging from the latent period of potentials arising in the visual cortex in response to stimulation of the superior colliculi these connections have one synaptic relay in the thalamus. The much shorter latent periods of visual evoked potentials recorded in the tectum of the monkey than in turtles (under identical chronic experimental conditions) confirm the views of morphologists on the progressive development of the tectal division of the visual system in vertebrate phylogeny. It is concluded that corticalization of both divisions of the visual system, i.e., the existence of telencephalic representation, appears in the early stages of vertebrate evolution.     

Heterogeneous hemoglobin system in anemic rats]

Fractional contents of hemoglobins of the peripheral blood, spleen and the bone marrow was studied in intact and anemic rats by using electrophoresis in polyacrylamide gel. Anemia was caused by injection of phenylhydrazine (HCl) into the animals. The principal regularities in the formation of the heterogeneous system of hemoglobin, depending on its source and the animal condition, was established. Possible mechanisms responsible for the rebuilding of the fractional contents of the protein investigated and its biological sense are discussed.     

Morphology of Newcastle bacteriophages]

A study was made of morphology of 6 clones of Newcastle bacteriophages of different origin divided into 3 types. Bacteriophage H-18 referred to the III morphological type by the Tikhonenko classification was characterized by a comparatively short process and a head in the form of an isometric polyhedron; H-1, H-5, H-10 and H-17 bacteriophages referred to type V, despite their antigenic difference were morphologically identical: they had a comparatively large head in the form of an elongated polyhedron and a process with a complicated structure ending by a besal plate with 3 indentions originating from it. Bacteriophage H-4 was referred to the IV type and was characterized by a head in the form of an elongated polyhedron and a long curved noncontracting process; in difference from the others it had no basal plate on the end of the process. The revealed morphological peculiarities of the particles of the Newcastle bacteriophages only partially correlated with their division on the basis of serolological properties and the size of the negative colonies.     

Renin-angiotensin-aldosterone system in rats with neurogenic stress]

A moderate neurogenic stress was induced in adult male rats by crowding for a period of 1 and 7 days. The content of angiotensin I and the activity of renin in the blood plasm aldosterone concentration in the peripheral blood plasma considerably. Seven days after the beginning of the neurogenic stress the content of aldosterone in the blood plasma considerably. Seven days after the beginning of the neurogenic stress the content of aldosterone in the blood and the adrenal tissue was determined radioimmunologically. Crowding of rats for 24 hours led to a marked increase of aldosterone content in the adrenal glands, failed to alter the content of this hormone in the blood, decreased the activity of renin and angiotensin I content in the blood and the adrenal glands of rats proved to fall; as to the activity of renin and the amount of angiotensin I in the peripheral blood plasma - it rose. The problem on the causes of dissociation observed in the renin-angiotensin-aldosterone system in response to the neurogenic stress of various duration is discussed.     

Neurotransmission at the interface of sympathetic and enteric divisions of the autonomic nervous system

The sympathetic and enteric divisions of the autonomic nervous system are interactive in the determination of the functional state of the digestive tract. Activation of the sympathetic input suppresses digestive function primarily through release of norepinephrine at its synaptic interface with the enteric nervous system. The enteric nervous system functions like an independent minibrain in the initiation of the various programmed patterns of digestive tract behavior and moment-to-moment control as the neural microcircuits carry-out the behavioral patterns. Most of the postganglionic projections from sympathetic prevertebral ganglia terminate as synapses in myenteric and submucous ganglia of the enteric nervous system. Two primary actions of the sympathetic input are responsible for suppression of motility and secretion. First is presynaptic inhibitory action of norepinephrine to suppress release of neurotransmitters at fast and slow excitatory synapses in the enteric neural microcircuits and this effectively shuts-down the circuit. Second is inhibitory synaptic input to submucosal secretomotor neurons to the intestinal crypts. The alpha, adrenergic receptor subtype mediates both actions. Axons of secretomotor neurons to the crypts bifurcate to innervate and dilate the submucosal vasculature. Dilitation of the vasculature increases blood flow in support of increased secretion. Sympathetic inhibitory input to the secretomotor neurons therefore suppresses both secretion and blood flow. Activation of the sympathetic nervous system cannot explain the symptoms of secretory diarrhea and abdominal discomfort associated with psychologic and other forms of stress. Current evidence suggests that brain to mast cell connections account for stress-induced gastrointestinal symptoms. Degranulation of enteric mast cells by neural inputs releases inflammatory mediators that enhance excitability of intestinal secretomotor neurons while suppressing the release of norepinephrine from postganglionic sympathetic axons. This is postulated to underlie the secretory diarrhea and abdominal discomfort associated with stress.