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Biomedical subjects

V I Lapsha

Publications and source records attributed to V I Lapsha.

At least 19 recordsLinked to original sources
PubMed2006

[Changes in the ultrastructure of histohematic barrier in the rat right atrium after short-term and prolonged heat stress].

In experiments on rats, changes of the ultrastructure of myocardial histo-hematic barriers in the right atrium during short-term and prolonged heat stress were studied. Short-term heat exposure (40 degrees C, 30 and 60 min) increased the rectal temperature by 3.0-3.5 degrees C. Immediately after heat exposure and 24 and 48 h following the exposure, the destructive and compensatory adaptive alterations in the microcirculatory bed were detected, accompanied by an edema of the pericapillary space and the changes in the size of mitochondria under the cardiomyocyte sarcolemma. Prolonged heating (40 degrees C, 4 h daily for 28 days) led to an increase in the rectal temperature by 0.4-1.6 degrees C. Changes in the microcirculatory bed had both dystrophic and compensatory adaptive nature. Erythrocyte and thrombocyte sludge and erythrocyte lysis were found in the lumen of microvessels. The number of endocytotic vesicles in endotheliocytes was variable; endotheliocyte nuclei had increased electron density and irregular outline. Myelin-like structures and apoptotic bodies were found in the pericapillary spaces. Under the cardiomyocyte sarcolemma the accumulation of mitochondria and sarcoplasmic vacuolization were noted. Comparison of short- and long-term effects of heat on histohematic barriers in the right atrium shows more significant changes after prolonged heat stress.

Animals↗
PubMed2005

[Structural and functional changes in the right atrium of the rats induced by short- and long-term heat stress].

In acute experiments performed on rats placed in heat-chamber (40 degrees C, 30- and 60-minutes-long exposure), an increase in NADPH-diaphorase (NADPH-d) and succinate dehydrogenase (SDH) activities were found in the neurons of intramural ganglia of the right atrium, while SDH and lactate dehydrogenase (LDH) activities were increased in cardiomyocytes. Hormone-producing cardiomyocytes, containing atrial natriuretic peptide, had numerous large secretory granules under the sarcolemma close to the microvessels. In contractile cardiomyocytes, the signs of early stage of apoptosis were observed including the subsarcolemmal accumulation of small mitochondria and cytoplasmic invaginations into the nucleus. Prolonged heating (37 degrees C, 4 h daily) led to an increased activities of NADPH-d and SDH in neurons of intramural ganglia of the right atrium and of NADPH-d and LDH in cardiomyocytes. Secretory granules in hormone-producing cardiomyocytes were small and reduced in number. Cardiomyocytes showing the signs of the late stage of apoptosis (with nuclear and cytoplasmic condensation) were demonstrated.

Animals↗
PubMed2004

Disaggregation of platelet aggregates formed by the action of thrombin in the presence of hydrogen peroxide.

The aggregation and change in the intracellular Ca2+ concentration induced by thrombin (0.005-0.22 U/ml) in the presence of H2O2 (0.05-0.6 mM) was investigated. Under the chosen experimental conditions (incubation time of platelets with H2O2 not more than 15 sec), H2O2 neither accelerated nor inhibited the thrombin-induced platelet aggregation. However, platelet aggregates formed by the action of thrombin in the presence of H2O2 were unstable and disaggregated. Disaggregation was abolished by catalase added after thrombin. The disaggregation effect was dose-dependent; the process of disaggregation was confirmed by electron microscopy. Hydrogen peroxide did not influence thrombin-induced increase in the intracellular Ca2+ concentration, but dose-dependently accelerated Ca2+ extrusion from the platelet cytoplasm.

Blood Platelets↗
PubMed2004

Changes in the activity of NO synthase, energy metabolism enzymes, and the ultrastructure of cerebral cortical neurons in a model of transient ischemia.

Experiments were performed on white male Wistar rats under Nembutal-urethane anesthesia. Transient ischemia (10 min) was produced by clamping of the carotid arteries. Some neurons in the parietal area of the cerebral cortex and endotheliocytes in blood vessels showed increases in NO synthesis and in the activity of energy metabolism enzymes (SDH, LDH). Changes in the ultrastructure of some neurons and synaptic formations provided evidence of a state of functional pressure, while changes in others indicated irreversible changes (disturbances in lipid metabolism and destructive changes in the nucleus and cytoplasm).

Animals↗
PubMed2003

[Changes in the activity of NO-synthase, energy metabolism enzymes and ultrastructure in neurons of the cerebral cortex in the model of short-term ischemia].

Experiments were performed on male Wistar rats under nembutal-urethan anesthesia. Short-time (10 min) cerebral ischemia was induced by bilateral ligation of carotid arteries. This was followed by an increased synthesis of NO and activity of energy metabolism enzymes (SDH, LDH) in a part of neurons of the parietal cortex and in endotheliocytes of blood vessels. The ultrastructural changes of some neurons and synaptic formations indicated functional tension, while in the others the irreversible changes (disturbed lipid metabolism, destructive alterations of the nucleus and cytoplasm) were found.

Animals↗
PubMed2001

[Changes in the afferent activity of the vagus nerve and the rectal temperature in rats following Escherichia coli endotoxin administration].

In anaesthetised rats, i.p. administration of the Echerichia coli lipopolysaccharide in doses 5 mcg/kg (LPS) increased afferent activity of the cervical vagus, whereas 100 and 1000 mcg/kg doses inhibited the afferent discharges. Pyrogen-free saline (PFS) did not alter the activity. Rectal temperature (RT) was decreased by the PFS and by large doses of the LPS. Sodium salicylate administration prevented the effects.

Afferent Pathways↗
PubMed1998

[Structural changes in the pelvic plexus in cold stress].

Alterations caused by hypothermal stress in neurons of pelvic plexus in rats were studied histochemically. The increase of catecholamine content in neurons and serotonin--in small intensely fluorescent cells (SIFC), suppression of acetyl cholinesterase activity in neurons were demonstrated after the short-term hypothermal stress leading to moderate hypothermia. Cooling of rats following the preliminary section of pelvic nerves does not prevent the above mentioned changes in neurons and SIFC. The participant of adrenergic nerves and SIFC in peripheral mechanisms of thermoregulation is under discussion.

Animals↗
PubMed1992

[Cytophotometric and electrophysiologic analysis of the role of the celiac plexus in maintaining temperature homeostasis in cold stress in rats].

The role of the celiac plexus in maintaining temperature homeostasis in rats during cold stress was studied histochemically, ultrastructurally, and electrophysiologically. Inhibition on efferent impulses in preganglionic (splanchnic) nerves and facilitation in postganglionic (superior mesenteric) nerves during a short-term cold exposure leading to slight hypothermia were found. In cold-exposed animals after the celiac plexus decentralization, the neurons showed an increase in the fluorescence intensity and activity of energy metabolism enzymes, hyperplasia of fine structures responsible for protein synthesis and energy supply of cells. It is suggested that during cold stress when efferent impulse flow in preganglionic nerves markedly decreases, the celiac plexus becomes a regulatory centre for autonomic functions involved in the maintenance of temperature homeostasis.

Animals↗
PubMed1991

[Effect of temperature and emotional factors on the catecholamine content in intestinal and splenic adrenergic plexuses of celiac plexus-decentralized rats].

Effects of temperature and emotive factors on the catecholamine content in intestinal and splenic adrenergic plexuses of celiac plexus-decentralized rats have been studied using histofluorescence and computer analysis. It is shown that the catecholamine content in the plexuses gets higher during hypothermia and remains unchanged during hyperthermia and emotional stress.

Animals↗
PubMed1990

[A cytophotometric study of the monoamines and energy metabolism enzymes in the neurons of the paravertebral ganglia under cold-induced and emotional stress].

The content of monoamines and energy exchange enzymes in neurons of the stellate ganglion (SG) and Th6-Th10 thoracic sympathetic trunk ganglia (TSTG) was studied histochemically using a computer analysis. Intensification of the monoamine fluorescence and energy exchange enzyme activity in SG neurons was found both during cold and emotional stress. Similar changes in TSTG were observed only during hypothermia. A selective activation of neurons of the paravertebral ganglia under different stresses is suggested.

Animals↗
PubMed1990

[The content of catecholamines in the adrenergic plexuses of the spleen and intestines during cold and emotional stresses].

The content of catecholamines in adrenergic plexuses of the spleen and small intestine of rats has been studied histochemically using a computer analysis. It is shown that the content increases both during the short-term cold and emotional stress. Intraperitoneally administered guanethidine (10 mg/kg) does not prevent cold-induced accumulation of catecholamines in these adrenergic plexuses, but the emotional-induced one remains. Putative mechanisms of the catecholamine accumulation in the splenic and small intestinal adrenergic plexuses during different stresses are discussed. It is suggested that the cold stress induces an increase of the catecholamine synthesis in adrenergic terminals of prevertebral ganglion neurons, whereas emotional stress leads to the catecholamine uptake by adrenergic terminals from the blood.

Adrenergic Fibers↗
PubMed1989

[Changes in the catecholamine level and energy metabolism of the myocardium in rats during cold and emotional stress].

The catecholamine content in adrenergic plexuses and the oxidative enzyme activity (succinate dehydrogenase, lactate dehydrogenase) during cold and emotional stress were studied histochemically in the rat myocardium. An acute short-term cooling led to an increase in the catecholamine fluorescence intensity and succinate dehydrogenase activity, whereas a short-term emotional stress resulted in a decrease in both these parameters.

Adrenergic Fibers↗
PubMed1988

[Cytophotometric study of catecholamines and energy metabolism enzymes in the neurons of the rat celiac plexus during cold and emotional stresses].

The content of catecholamines and activity of the energy metabolism enzymes in neurons of the celiac ganglia during cold and emotional stress were studied histochemically using a computer analysis. It was shown that acute short-term cooling increased catecholamine fluorescence intensity, as well as succinate dehydrogenase and lactate dehydrogenase activity in the celiac ganglia neurons, whereas short-term emotional stress induced no changes in the fluorescence intensity and enzyme activity.

Animals↗
PubMed1986

[Microfluorimetric study of adrenergic structures in nerve plexuses of the pelvic cavity of the normal and decentralized cat].

Microfluorimetric technique was used to study catecholamine concentration in small intensely fluorescent (SIF) cells and in adrenergic fibres of the pelvic plexus ganglia and intramural ganglia of the cat urinary bladder and rectum in control and following sympathetic and parasympathetic denervation. Two types of SIF-cells were studied: cells of the first type contained catecholamines and those of the second type--serotonin. Parasympathetic denervation resulted in an increase of SIF-cells which exhibited serotonin fluorescence, and in more intense fluorescence of adrenergic fibres in the pelvic plexus ganglia and intramural ganglia of the urinary bladder, not affecting the intensity of fluorescence of the adrenergic fibres in the intramural ganglia of the rectum. Sympathetic denervation did not alter the fluorescence intensity in SIF-cells and adrenergic fibres in the pelvic plexus ganglia and urinary bladder and led to almost complete disappearance of the adrenergic fibres in the intramural ganglia of the rectum.

Adrenergic Fibers↗
PubMed1985

[Cytophotometric study of catecholamines and acetylcholinesterase in neurons of the intramural plexus of the urinary bladder of the cat in controls and animals exposed to experimental conditions].

The intramural plexus of the cat urinary bladder was studied with histochemical methods for catecholamines and acetylcholinesterase. Ganglia of the plexus showed differences in the number of neurons (5 to 150 cells). They were adrenergic, cholinergic or mixed. Section of pelvic nerves increased the amount of catecholamines in adrenergic neurons and fibres and decreased the acetylcholinesterase activity. Section of hypogastric nerves did not affect the catecholamine level and acetylcholinesterase activity.

Acetylcholinesterase↗
PubMed1985

[Electrophysiologic and histochemical characteristics of the fiber composition of the subdiaphragmatic portion of the vagus nerves].

The fibre composition of subphrenic branches of the vagus nerves was studied electrophysiologically and histochemically. In anaesthetized cats, the presence of multicomponent electrical responses was found during stimulation of preganglionic fibres of splanchnic nerves in the splanchnic branch of the dorsal vagus trunk; the presence of synaptically interrupted fibres was shown. Histochemically, adrenergic fibres were found both in the central and in the peripheral stumps of subphrenic branches of the vagus nerves. Most strongly fluorescent fibres were regularly found in the peripheral stump of the splanchnic branch of the dorsal vagus trunk. The data obtained suggest that processes of ganglionic neurons of the celiac plexus ascend within splanchnic and other branches of the vagus nerves.

Adrenergic Fibers↗
PubMed1984

[Ratio of adrenergic and cholinergic structures in the prevertebral sympathetic and parasympathetic ganglia].

Histochemical techniques for catecholamines and acetylcholinesterase revealed the ratio of adrenergic and cholinergic neurons in sympathetic (celiac and inferior mesenteric) and parasympathetic (pelvic) plexuses of the abdominal and pelvic cavities. Three types of ganglia were revealed in the pelvic plexus, i.e. cholinergic, adrenergic, and of mixed type. Adrenergic fibers were found in preganglionic nerves both to sympathetic and parasympathetic plexuses. A centripetal transport of catecholamines through axons of adrenergic neurons located in extramural ganglia, was shown.

Acetylcholinesterase↗