PubMed Health⌕ Search

Biomedical subjects

M Moravec

Publications and source records attributed to M Moravec.

At least 19 recordsLinked to original sources
PubMed1990

Catecholaminergic and peptidergic nerve components of intramural ganglia in the rat heart. An immunohistochemical study.

Immunohistochemical properties of the terminal nerve network in the rat heart were assessed by use of the elution-restaining method. The colocalization of the enzymes involved in catecholamine synthesis (tyrosine hydroxylase--TH. dopamine-beta-hydroxylase--DBH) as well as the respective distributions of the neuropeptides associated with the adrenergic nervous system (neuropeptide tyrosine--NPY, C-terminal flanking peptide of neuropeptide Y--C-PON) were studied in series of serial sections throughout the interatrial septum and the atrioventricular junction. Our data suggest that ganglion cells of sulcus terminalis as well as the epicardial ganglia enclosed between the superior vena cava and ascending aorta are VIP- and TH-negative, but neuropeptide Y- and DBH-immunoreactive. They give rise to three intraseptal nerves directed towards the specialised structures of the atrioventricular junction. These nerve fascicles contain abundant, thick TH-immunoreactive nerve fibres and scarce, thin NPY- and DBH-immunoreactive fibres. The cell bodies of the intramural ganglion cells localized between the right and left branches of the bundle of His (Moravec and Moravec 1984) are strongly TH- and DBH-immunoreactive. They are innervated by thick nerve fibres having the same immunohistochemical properties (NPY- and DBH-immunoreactivities) as those of a subpopulation of the epicardial ganglion cells and seem to supply some of the TH-immunoreactive nerve fibres directed via the intraseptal nerves to the epicardial ganglia. The existence of a multicomponent nerve network, characterized by a reciprocal innervation of the sinus node and atrioventricular node areas, is suggested by our immunohistochemical data.

Animals↗
PubMed1990

Catecholamine-synthesizing enzymes and neuropeptides in rat heart epicardial ganglia; an immunohistochemical study.

The subepicardial atrial ganglia of rat hearts were examined using immunohistochemical techniques and antibodies against the catecholamine-synthetic enzymes tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DBH), and the neuropeptides substance P (SP), calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP) and met-5-enkephalin (ENK). Some of the ganglion cells present in the ganglia exhibited DBH-like immunoreactivity (LI) and NPY-LI, whilst these cells never exhibited TH-, VIP-, CGRP-, SP- or ENK-LI. Groups of small cells exhibiting an intense TH-LI, corresponding to cells referred to as catecholamine-containing cells and sometimes small intensely fluorescent cells in the literature, were observed in the ganglia. A subpopulation of these cells exhibited immunoreactivity to one of the neuropeptides tested, namelyu SP. Only a few of the cells showing TH-LI displayed DBH-LI. Nerve fibres showing SP-, CGRP-, DBH- and TH-LI were present in the ganglia; some of these fibres being closely associated with the ganglion cells or with the cells showing TH-LI. The observation provide new information on the catecholamine-synthetic enzyme/neuropeptide expression of the ganglion and catecholamine-containing cells and of the associated nerve fibres of rat heart subepicardial ganglia.

Animals↗
PubMed1989

Adrenergic neurons and short proprioceptive feedback loops involved in the integration of cardiac function in the rat.

Serial cryostat and paraffin-embedded sections through the atrioventricular junction of the rat heart were studied at the light-microscopic level after indirect immunohistochemical staining (tyrosine hydroxylase, neuropeptide Y, C-terminal flanking peptide of neuropeptide Y immunoreactivities) or silver impregnation. The distribution of these immunoreactivities in the Hissian ganglion (Moravec and Moravec 1984) as well as the relationships of the Hissian ganglion cells with the surrounding structures have been studied to assess its function. The results suggest that the Hissian ganglion is composed of large multipolar neurons displaying both tyrosine hydroxylase (TH) and related peptide (neuropeptide Y. C-terminal flanking peptide of neuropeptide Y) immunoreactivities. The dendritic projections of these adrenergic cells penetrate the reticular portion of the atrioventricular node and the upper segments of the interventricular septum where they constitute sensory-like corpuscles. The hypothesis that the adrenergic neurons of the atrioventricular junction are involved in short proprioceptive feedback loops necessary for beat-to-beat modulation of cardiac excitability and intracardiac conduction can thus be suggested.

Adrenergic Fibers↗
PubMed1986

Intrinsic neurosecretory neurons of the rat heart atrioventricular junction: possibility of local neuromuscular feed back loops.

The microanatomy and ultrastructure of rat heart atrioventricular junction were studied on serial sections of both paraffin and epoxy embedded samples. The animals were pretreated with 5-hydroxy-dopamine in order to differentiate the adrenergic component of the terminal nerve plexus. Two kinds of ganglia could be identified throughout the interatrial septum by the optical microscope. The first was composed of large pale cells with voluminous nuclei. The other resembled acini-like clusters of osmophilic cells. Another small ganglion was invariably present between right and left branches of the bundle of His. The electron microscopic examination of this structure revealed, apart from small pale neurons (10 microns in diameter), several large 5-hydroxy-dopamine contrasted neurosecretory cells (up to 30 microns) with abundant electron dense vesicles typical for sympathetic neurons. Numerous glomeruli with dendrodendritic and axodendritic connections, some of which exhibit the same 5-hydroxy-dopamine loaded vesicles, could be found in the vicinity of the specialized conducting tissue. The functional implications of the above morphological data are not clear. However, the intrinsic neurosecretory component can be expected to modulate both specialized cells and neighbouring neurons. The heterogeneity of neuro-neuronal and neuro-muscular relations, such as perinodal mechanoreceptors, may suggest that the terminal nerve plexus not only distributes the efferent stimuli, but that it also has an integrative function which is the necessary prerequisite for a local feed back autoregulation.

Animals↗
PubMed1985

Terminal nervous plexus of the atrioventricular junction of the rat. Microanatomical aspects and regional specialization.

The paraformaldehyde-fixed hearts of adult rats were embedded in paraffin. Serial sections throughout the interatrial septum and the atrioventricular junction were examined in the optical microscope after having been silver stained. The density and the distribution of different nervous elements in the perinodal nerve plexus were studied and the results compared with the electron-microscopic data. These data confirm that at the level of the atrioventricular junction, a dense terminal network can be seen. It is composed of both terminal nerve fibers and ganglionic cells forming a small ganglion adjacent to the lower edge of the bundle of His and a thin ganglionic lamina in the interatrial septum. Apart from small neurons, previously described as cholinergic, large neurosecretory cells could also be demonstrated in some of the serial thin sections through the Hissian ganglion. The neuromuscular junctions between the terminal nerve fibers and specialized cells exhibit regional specialization. While the distal portion of the atrioventricular node and the bundle of His receive essentially efferent fibers, afferent coiled endings prevail in the reticular portion of the atrioventricular node and in the adjacent interatrial septum. Similar structures, larger in diameter, can also be seen around the muscular fibers and around the capillaries of the interventricular septum. The functional significance of the aforedescribed regional specialization of the terminal innervation of the atrioventricular junction is briefly discussed.

Animals↗
PubMed1984

Intrinsic innervation of the atrioventricular junction of the rat heart.

Alternate serial semithin and thin sections of the glutaraldehyde-fixed interatrial septum and atrioventricular junction of adult rat were examined in light and electron microscopes. The animals were pretreated with a false precursor of catecholamines, i.e., with 5-OH-dopamine, in order to differentiate the adrenergic component of the intrinsic nervous system. According to the light microscope data, two kinds of ganglia can be distinguished at the level of the interatrial septum. Those of the first kind are composed of large pale cells with voluminous nuclei. Those of the other kind resemble acinuslike clusters of small osmiophilic cells. Another small ganglion is invariably associated with the distal edge of the bundle of His. At the electron-microscope level, two types of ganglionic cells are found in the meshes of the peri- and intranodal plexus: 1) small neurons (10 microns) with richly developed neuropiles, and 2) large 5-OH-dopamine contrasted neurosecretory cells (up to 25 microns) containing electron-dense vesicles typical of sympathetic neurons. Numerous glomeruli with dendrodendritic and axodendritic connections are also found in the vicinity of the specialized tissue; and, in the nodal interstitium, several clusters of small chromaffin cells (5 microns) and a network of multipolar satellite cells similar to the interstitial cells of Cajal can be distinguished. Our data suggest that the microanatomical and cytological organization of the terminal innervation of the node of Aschoff-Tawara and of the bundle to His resembles that of the myenteric plexus. The physiological significance of these ultrastructural data for the local control of electrophysiological properties of the atrioventricular junction is briefly considered.

Animals↗
PubMed1981

Some morphological aspects of the atrioventricular junction in the rat heart.

The interrelationships of different components of atrioventricular junction of the rat heart were examined on serial sections. The results are the following: 1) The atrioventricular node of the rat is situated at the level of membraneous septum separating left ventricular cavity from the right atrium. This particular localization may be of functional significance since at this level both the state of systemic arterial circulation and venous return, can be integrated. 2) Apart from the node of Aschoff-Tawara adjacent to the upper edge of muscular septum, an accessory atrioventricular node is regularly present close to the aortic root. 3) In the proximity of both atrioventricular nodes we found vascular lacunae containing abundant mastocytes and chromaffin cells. These pictures seem to suggest the existence of local chemoregulation and transmitter liberation. 4) His bundle is apposed to subendocardial fibrous lamina running from mitral valve to the cartilaginous ring of the aortic root. This association of specialized cells with their connective environment reminds the organization of different mechanoreceptors described in literature.

Animals↗
PubMed1980

[Origin and pathogenesis of polymeric dipyrrilmethenes].

By means of the silicagel thin layer chromatography and spectrophotometry the qualitative differences of the polymeric dipyrryl methenes in the bile and in the urine in normal and pathological conditions were demonstrated. The differences between the polymeric dipyrryl methenes of fresh hepatic bile and the polymeric dipyrryl methenes of the older hepatic and fresh duodenal bile were found. The same differences were found in the urine between the normal urinary polymeric dipyrryl methenes and the polymeric dipyrryl methenes in the hyperhemolytic state and in the bile duct obstruction. An entirely different quality of the polymeric dipyrryl methenes in the urine is to be admitted in the liver diseases.

Anemia, Megaloblastic↗
PubMed1979

[Contribution of ultrastructural analysis to the knowledge of the neuromuscular relationships in the nodal and conduction tissue].

The ultrastructure of the atrio-ventricular junction in the rat heart fixed in situ was studied on serial fine sections. The relationships between the specialized tissue and the nervous system were studied after labelling adrenergic endings with 5-OH-dopamine. Among the various types of nerve endings a distinction may be made between: 1) adrenergic or cholinergic free endings; 2) large "cluster" endings of the cholinergic types, seen mainly in the equatorial regions of nodal cells; 3) small diameter cholinergic before the development of heart failure or significant card synaptic images; 4) afferent neurons, whose endings, rich in glycogen and mitochondria supply the conduction tissue fibres, getting into or through the muscle fibre. The intermembrane space is then 20 nm. The analogy between the images observed and the ultrastructural aspects of intrafusorial fibres in skeletal muscle is discussed.

Adrenergic Fibers↗
PubMed1975

[The rat ventricular myocardium in chronic hypercapnia. Electron microscopic study].

An electron microscope study of the left ventricular myocardium from rat acclimatized to chronic hypercapnia was done in order to complete the preceding work concerning general effects of respiratory acidosis. After 15 and 30 days of the acclimatation to 8% CO2 no lesions of the myocardium could be found. The results of the morphometric analysis indicated, however, discrete modifications of heart ultrastructure similar to those found before in hypoxic and failing hearts: namely a decrease of mitochondrial mean diameter and a non significant decrease of mitochondrial fractional volume. The latter was accompanied by a significant decrease of myofibrillar mass. The presence of cellular oedema seems to be suggested by an increase of fractional volume of the cytosol. The mechanism of these changes is not easy to explain. Further work will be necessary to make a choice between two possibilities: (1) depressed contractility related to some direct effect of high pCO2 and (2) tissue hypoxia secondary to local effects of the former.

Animals↗