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At least 847 records · Page 47Linked to original sources
PubMed1999

Comparison of K(+)-p-nitrophenyl phosphatase activity in the urinary bladder of the frog Rana esculenta during hibernation and active life.

We have studied effects of hibernation on the frog urinary bladder, an organ involved in water and ion transepithelial transport and taking part in osmoregulation. We have demonstrated K(+)-p-nitrophenyl phosphatase activity (an enzyme involved in ion and water transport) both in active and hibernating frogs. Most of the reaction product deposition was found on basolateral membranes of granular cells of the urinary bladder epithelium during all seasons. Therefore, it seems likely that this organ, unlike organs studied previously (skin, kidney and lung), maintains its function in the osmoregulatory process during hibernation.

4-Nitrophenylphosphatase↗
PubMed2000

[Seasonal characteristics of the monoaminergic regulation of the behavior of hibernating animals].

The stimulating effect of L-DOPA on exploratory activity of the ground squirrel in the hole-board and open field experiments was stronger in the spring than in autumn, whereas the regulating effect of the 5-HTP on adaptive behaviour of hibernating animals was stronger in autumn. Results of the biochemical analysis of the MAO A activity with serotonin or noradrenaline as substrates revealed a seasonal dependence of the substrate specific changes of this enzyme activity in hibernating animals. The data obtained suggest that the seasonal distinctions in effects of similar pharmacological agents depend on activity of the brain monoaminergic systems' activity in hibernating animals in different periods of the annual cycle.

5-Hydroxytryptophan↗
PubMed2000

The regulation of L-type Ca2+ currents in cardiac myocytes of hibernating animals.

The action of isoproterenol and BAY K 8644 on voltage-dependent Ca2+ currents in isolated ground squirrel cardiac myocytes was studied in two (active and hibernating) states of the animal. In cardiac myocytes of active animals the effect of both drugs was shown to depend on the holding potential. At Vh of about -50 mV both isoproterenol and BAY K 8644 increased the Ca2+ current and their action was additive. At Vh of about -20 mV, both drugs inhibited the Ca2+ current. In cardiac myocytes from hibernating animals, isoproterenol increased the Ca2+ current at any holding potentials, while the effect of BAY K 8644 did not differ significantly from its effect on active animals. The combined action of the two drugs caused the inhibition of the Ca2+ current at high holding potentials. In terms of the two-site Ca2+ channel model, this means that one of the two pathways of channel phosphorylation is blocked in hibernating animal cardiac cells, and BAY K 8644 restores this pathway.

Animals↗
PubMedDate not supplied

[Changes in the isoform composition of the cytoskeletal protein titn--adaptation process in hibernation].

Changes in the isoform composition of the elastic protein titin from skeletal and cardiac muscles of hibernating ground squirrels were revealed for the first time. It was shown that, upon hibernation, the molecular mass of titin decreases and its functional properties change as compared with the active state of the animal. The physiological significance of the changes in titin isoform composition for the inhibition of muscle contractile activity upon hibernation is discussed in connection with similar changes during some cardiomyopathies.

Animals↗
PubMed1975

Comparative studies of blood from hibernating and nonhibernating European hamsters (Cricetus cricetus L).

The blood of 6 male and 6 female European hamsters (Cricetus cricetus L) was examined in summer, in winter before hibernation, and 1 da after awaking from hibernation. Blood was drawn from a sublingual vein under ether anesthesia in nonhibernating animals. No influence of hibernation upon the number of erythrocytes and the differentials was found, whereas the number of thrombocytes and leukocytes were reduced to a minimum. From the unchanged numbers of thrombocytes and leukocytes in nonhibernating animals during winter, the influence on the blood of a seasonal cycle independent of hiberation was excluded.

Animals↗
PubMed1975

[Cytoplasmic RNA content in the brain and spinal cord neurons of red-cheeked susliks during the hibernation period and on arousal].

By means of scanning cytospectrophotometry of gallocyanin chrome alum stained sections, cytoplasmic RNA content per cell in the neurons of the ground squirrel hippocampus, hypothalamic supraoptic nucleus, and spinal cord anterior horns, was shown to decrease as far as the hibernation went on. Before the arousal the RNA amount increased, the increase being the greatest in the hypothalamic neurons. First days after the arousal, the cytoplasmic RNA content in all the neurons was significantly higher than in the same neurons before the hibernation. Changes of RNA content in the neurons and in the homogenates of corresponding brain areas were compared; important role of the hypothalamus in metabolic reconstruction of the nervous system at various stages of hibernation, was outlined.

Animals↗
PubMedDate not supplied

[Modulation of neuronal evoked responses to the medial septal area of hibernating ground squirrels by some neuropeptides after chronic disconnection between septum and preoptico-hypothalamic structures].

Effects of some neuropeptides identified in the brain of hibernators (TSKYR, TSKY, DY) and of monoaminergic neurotransmitters (noradrenaline and serotonin) on responses of the medial septal neurons evoked by intraseptal electrical stimulation were analyzed in slices taken from the ground squirrels with chronic basal undercutting of the septum. Despite the elimination of direct contacts with the preoptic area and afferents ascending in the medial forebrain bundle, the neurons retained almost normal level of reactivity and distribution of the reaction types. The neuropeptides effectively modulated neuronal responses of various types, including oligosynaptic short-latency single-spike responses. The latter were strongly facilitated by the neuropeptides. As a rule, changes in the responses to electrical stimulation were independent of the spontaneous activity shifts (in 78% of the tests). It was suggested that the neuropeptides exert a double influence on the septal neurons: direct nonsynaptic effects on the pacemaker potential responsible for the background activity and modulation of synaptic processes. Our experiments showed that descending influences of the septo-hippocampal system are not crucial for the entrance into the hibernation state and its tonic maintenance. The influences of the thermoregulatory--circadian structures of the preoptico-hypothalamic area determine the paradoxically increased latent excitability of septal neurons that allows the septo-hippocampal system to gate external stimuli and organize arousal of the forebrain during hibernation in case of emergency.

Animals↗
PubMed1992

[The role of dermorfin in regulating hibernation processes in mammals].

Administration of dermorphin (0.1 mg/kg, subcutaneously) induced a drop of body temperature, deceleration of initial vegetative parameters and development of hibernation-like state in susliks. The delayed effects involved a disorder in conditioning. The immunisation of hibernating susliks with the dermorphin conjugate leads to a gradual waking up of the animals, normalising of conditioning in all the parameters and occurrence of a motor component in avoidance conditioning. A possible specific role of the dermorphin in the mechanisms of hibernation, is discussed.

Acoustic Stimulation↗
PubMedDate not supplied

[Cerebral synaptosome ATPase activity in Citellus erythrogenys susliks during periods of wakefulness and hibernation].

The activity of synaptosomal Mg- and Na, K-ATPases has been compared during natural hibernation and active periods in ground squirrels. Being assayed in vitro at temperature 37 degrees, the activity of Na, K-ATPase decreases during hibernation by 25%, that of Mg-ATPase--by 37%. The decreased level of the activity of these enzymic systems may result from structural alterations in the brain membranes during hibernation of the animals.

Adenosine Triphosphatases↗
PubMed1992

Some aspects of lipid metabolism and thyroid function in arctic ground squirrel, Citellus parryi during hibernation.

The increased blood levels of thyroid hormones as well as morphologic signs of high activity of thyroid gland were observed in arctic ground squirrel during hibernation. High thyroid activity could explain the characteristics of lipid metabolism observed in the studied species during hibernation-increased lipid unsaturation and decreased cholesterol/phospholipids molar ratio in plasma membranes. High blood concentrations of total lipids, cholesterol, and phospholipids in dormant animals is explained by the dissociation between thermogenic and lipotropic actions of thyroid hormones. We postulate that thyroid hormones participate in long-term regulation of body energy metabolism and of homeoviscous adaptation of membranes during hibernation.

Animals↗
PubMed2004

[Apoptosis and hibernation of cardiomyocytes of periscar zone as factor of chronic cardiac aneurysm progression].

Tissue specimen from chronic aneurysms and adjacent myocardium obtained at aneurysmectomy and coronary bypass surgery from 46 patients were subjected to morphological study. Immunohistochemical methods and electronic microscopy were applied for detection of apoptosis and hibernation of cardiomyocytes in 11 cases and histochemical determination of activity of energetic enzymes succinate and lactate dehydrogenase was used in 5 cases. Cardiomyocytes from peri and intra scar layers of myocardium were found to be in a state of hibernation while some of them were in a state of apoptosis. Extent of apoptosis was different in aneurysms on different stages of organization. Number of altered cardiomyocytes was the greatest in immature aneurysms. Basing on these findings apoptosis of hibernating cardiomyocytes was suggested to be one of factors of expansion of sclerotic zone and aneurysm formation.

Apoptosis↗
PubMedDate not supplied

[The role of medial septal area in the neural control over hibernation].

Hibernation (winter sleep) is a kind of unique adaptive behavior of small mammals subjected to fine and complex central control. One of the most promising approaches to this problem is a search for the mechanisms providing brain control under conditions of a sharp decrease in temperature, (virtually, to zero) and metabolic rate. Studies conducted at the Laboratory of System Organization of Neurons under the supervision of Professor O.S. Vinogradova confirmed the hypothesis of the special role of the septohippocampal system in the control of winter sleep. Together with a brief characterization of hibernation in general, the data obtained at the Laboratory are also summarized in the review. The experimental evidence for the role of the medial septal area as a "sentry post" in hibernation is presented.

Adaptation, Physiological↗
PubMedDate not supplied

[Specifics of monoaminergic regulation of the central nervous system of hibernating animals (Citellus undulatus)].

Seasonal features of open-field behavior of Yakut ground squirrels (Citellus undulatus) and changes in the brain MAO A activity were studied. It was found that all parameters of exploratory activity in the open field and holeboard test reached the values characteristic of summer animals very rapidly, within a few days or (in some cases) even within the first 24 hours after the arousal from hibernation in the middle of April. In autumn these parameters decreased to their minimum values 1.5-2 months prior to hibernation. Biochemical analysis showed that in April the activity of MAO A measured with serotonin as a substrate in the hippocampus was 1.8 times (p < 0.05) higher than the activity of MAO A with respect to noradrenaline. In contrast, in autumn the MAO A activity determined with noradrenaline as a substrate was 2.5 (p < 0.05) times higher than the activity a MAO A with respect to serotonin. Taken together, these data indicate that the seasonal features of the higher nervous activity of hibernating animals depend on the balance between serotonergic and noradrenergic systems in different periods of the annual cycle.

Affect↗
PubMedDate not supplied

[Adaptive behavior of titin isoforms from skeletal and cardiac muscles of ground squirrels (Citellus undulatus) during hibernation].

By the use of modified SDS electrophoresis in agarose-strengthened 2% polyacrylamide gels, the adaptive behavior of titin isoforms in skeletal and cardiac muscles of ground squirrels (Citellus undulatus) during hibernation was studied. The presence of two titin isoforms (short and long) with molecular weights approximately 3700 and approximately 3800 kDa in m. soleus, approximately 3400 and approximately 3600 kDa in m. psoas, approximately 3000 and approximately 3400 kDa in the left ventricle of myocardium was found. It was found that the content of the short titin isoform in the above muscles of hibernating and arousing ground squirrels is considerably lower than that of the long titin isoform. The preservation of the long titin isoform in skeletal and cardiac muscles of hibernating and arousing ground squirrels can be regarded as an evolutionarily determined adaptive mechanism favoring the survival of animal under extreme conditions without pathological consequences.

Animals↗
PubMedDate not supplied

[The evaluation of the sizes of erythrocytes of the hibernating ground squirrel Citellus undulatus Pallas].

A topographical image of individual erythrocytes of the ground squirrel Citellus undulatus Pallas, in unfixed unstained smears was first obtained by scanning probe microscopy for two states of the animal: hibernation and the active state. The scannig of single discocytes, i.e. erythrocytes having a typical discal form, was fulfilled. For the active male, the diameter of the discocyte was found to be approximately 6500 nm. For the hibernating female, the diameter is approximately 6000 nm. According to the data of light microscopy, the discocyte diameters are: 6610 +/- 100 nm for the active state of animal and 6430 +/- 160 nm for the hibernating state.

Animals↗
PubMed2005

[Pattern of excitation in isolated heart of hibernator ground squirrel Citellus undulatus].

Aim of our study was to measure conduction velocity and pattern of excitation during hypothermia in hearts of ground squirrels Citellus undulatus, known to be most resilient hibernators. We imaged electrical conduction in intact isolated hearts of summer active and winter hibernating ground squirrels at temperatures varying from +37 degrees C to +3 degrees C. Electrical activity was mapped using CCD camera (500 frames/sec) and voltage-sensitive dye di-4-ANEPPS during normal sinus rhythm and ventricular pacing. No spontaneous tachyarrhythmia was observed in all hearts at any temperature. Hearts were able to maintain spontaneous sinus rhythm and normal pattern of epicardial excitation throughout the whole range of studied temperatures. Despite responsiveness to pacing in all hearts ventricular conduction velocity was significantly reduced (about 10-fold) at low temperatures +3 degrees C. Our data provides the first direct demonstration that isolated heart of the summer active and winter hibernating ground squirrel Citellus undulatus is able to maintain normal excitation pattern in a range of temperatures from +37 degrees C to +3 degrees C.

Animals↗
PubMed1991

[Oxidative activity and Delta(Psi) of liver mitochondria of active and hibernating ground squirrels during various incubation conditions].

A comparative analysis of delta psi of liver mitochondria of active and hibernating gophers was carried out, and the effect of the decrease of the medium tonicity on the oxidase activity and delta psi of liver mitochondria of both animal groups was studied. The delta psi of hibernating gopher liver mitochondria was shown to be lower than that of active animals mitochondria and displayed a higher sensitivity to the uncoupler and some different restoration dynamics after the decline following the ADP addition. Swelling of liver mitochondria of hibernating gophers in hypotonic media or in media containing potassium acetate and a 3-fold freeze-thawing procedure resulted in the enhancement of the oxidase activities accompanied (in case of hypotonicity) by an delta psi increase and a decrease of its sensitivity to the uncoupler, 2.4-dinitrophenol. Inhibition of phospholipase A2 prevented the enhancement of the oxidase activity in all cases and the delta psi increase in hypotonic media.

Adenosine Diphosphate↗
PubMed1990

[Morphological changes in pinealocytes during the hibernation bout in the Mongolian ground squirrel, Citellus dauricus].

Adult Mongolian ground squirrels (Citellus dauricus) were kept at 5 degrees C in winter and divided into four experimental groups according to the bout length. The first group was not hibernating until decapitation. The bout length of the second group was between 4-10 days, the third group 11-17 days and the fourth group longer than 20 days. All pineals were sampled at the end of January. Morphometric analytical procedures were used to study the ultrastructure of the distal part of the pineal gland. The statistical results demonstrated that 1) the euthermic animals have larger cross areas of pinealocyte, longer and narrower Golgi apparatus and more number of saccules of each Golgi apparatus (P less than 0.01). But they also have smaller volume density of vaculoes, less lipid droplets and associated vesicles around Golgi apparatus (P less than 0.01). 2) the hibernating animals with variety of bout length had no significant differences in the number of mitochondria, lipid droplets, lysosomes, the size of Golgi apparatus and the cross areas of nucleus and cytoplasm (P greater than 0.05). However, the number and the cross areas of vacuoles were significantly increased with the bout length (P less than 0.01). This might suggest that the bout length was not related to the metabolic activity of pinealocytes in Citellus dauricus and vacuoles might play some important roles in maintenance of individual bout of hibernation in this species.

Animals↗