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PubMedDate not supplied

[The cardiotropic, hypometabolic and hypothermic activity of peptide fractions from the tissues of hibernating cold-adapted animals].

From tissues of hibernating and active long-tailed ground squirrels and from the brain of cold-adapted Yakut horses, low molecular peptide fractions were obtained which, after injection to albino mice, decreased oxygen consumption and rectal temperature in them. The same fractions exhibited negative chrono- and inotropic effects on isolated hearts of ectothermic and endothermic animals. Fractions from the brain of ground squirrels and the brain of horse exhibited similar pattern of the activity. The activity of fractions was subjected to seasonal changes and depended on the degree of their purification. Provisional intracellular microelectrophysiological analysis of the effect of these fractions on the frequency and strength of contractions in isolated heart was made.

Adaptation, Physiological↗
PubMed1990

Electrolyte and water transport in the newt renal tubule due to the action of low-molecular fractions isolated from the intestine of the hibernating ground squirrel.

The micropuncture technique and X-ray microanalyses were used to evaluate Na, K, Ca, Mg, Cl and fluid transport in the early distal tubule mediated by low-molecular fractions isolated from the intestine of the hibernating ground squirrel (HSI). Perfusion of intertubular capillaries with a solution containing HSI with a molecular weight of 1-10 kD (0.1 mg.ml-1) decreased the relative reabsorption of fluid, Ca and Mg. The other low-molecular fraction 1-10 kD of m.v. (0.1 mg.ml-1) isolated from the intestine of alert ground squirrels (ASI 1-10) caused no significant changes of the ionic concentration and inulin concentration index in the distal tubule. Fraction 1 with molecular weight 1.2-4.5 kD (0.1 mg.ml-1) obtained by further division of HSI 1-10, decreased the reabsorption of fluid and ions under study. Fractions 2 (m.w. 0.98 kD) and 3 (m.w. 0.89 kD) had no effect on the ion and fluid transport in the same tubule. The addition of naloxone (0.4 mg.ml-1) blocked the action mediated by HSI 1-10 or fraction 1. Thus, the substance(s) capable of regulating Ca, Mg, and fluid transport in the distal tubule likely to be mediated by the opiate-dependent process has a molecular weight of 1.2-4.5 kD.

Animals↗
PubMed1990

[Characterization of the expression of LDH isozymes genes during non-hibernation Himalayan marmots].

The lactate dehydrogenase (LDH) isozymes from heart, liver, kidney and skeletal muscle in Himalayan marmots (Marmota himalayana robusta) in non-hibernation were investigated in the present experiment. The isozyme patterns were analyzed by means of disc electrophoresis and the ultraviolet enzymatic determination. The following conclusions were obtained: 1. It was found that two expression patterns of LDH genes presented in the skeletal muscle of Himalayan marmots. There was a LDH-B4 band only in one marmots and absent in others. The interindividual polymorphism of LDH isozyme patterns may be attribute to one or more regulator genes controlling synthesis of B-subunit of LDH. 2. LDH zymograms of various tissues of Himalayan marmots showed different subbands. This is presumably due to the existence of both symmetrical and asymmetrical conformers of this tetramer.

Animals↗
PubMed1985

[Proteins and RNA in the neuron-neuroglia system of the nucleus raphe dorsalis of the suslik brain during hibernation].

The concentration and the content per cell of total proteins were found to be considerably decreased during deep hibernation (in December) in the ground squirrel (Citellus pygmaeus Pall.) brain n. raphé dorsalis neurons, whereas in glial cells--satellites with the same concentration, the protein content reduction was lesser than in the neurons. Preceding the awakening (in March), the protein content in neuron cytoplasma increased, the protein concentration remaining equal to control, whereas the values related to gliocytes did not vary in March from those in December. In March, a considerable RNA content increase occurred in the neuron cytoplasma, its concentration remaining the same, whereas the RNA values in gliocytes approximated the control values (those of the animals in wakefulness).

Animals↗
PubMedDate not supplied

[An ultrastructural stereological analysis of the cardiomyocytes in a hibernating rodent (the red-cheeked suslik Citellus erythrogenys, Brandt)].

The quantitative morphological study of cardiomyocytes in heterothermic animals (red-cheeked susliks Citellus erythrogenys Br.) was quantitatively morphologically studied. The features of spatial ultrastructural cardiomyocyte reorganization in hibernating susliks were shown to manifest in pronounced increase of volume and surface densities of sarcoplasmic reticulum and relative volume of lipid droplets.

Animals↗
PubMedDate not supplied

[Dynamics of 3H-lysine incorporation into the retinal ganglion cells of the ground squirrel (Citellus pygmaeus Pallas) in active state and during hibernation].

Circahoralian rhythm of the intensity of 3H-lysine incorporation into proteins of the retina ganglionic cells and of the protein synthesis rate in the isolated retina with an amplitude of fluctuations of 35-36% of the mean has been found in active adult susliks. During hibernation, no circahoralian fluctuations of protein metabolism were recorded. Circahoralian rhythms of protein metabolism can serve as a marker of the tissue functional activity.

Animals↗
PubMedDate not supplied

[Electrophysiological characteristics of cardiac function and the intensity of protein synthesis in cardiomyocytes during the arousal of susliks from hibernation].

It has been demonstrated that during winter hibernation (body temperature 2-4 degrees C), the heart rate in ground squirrels is equal to 100 10-12 beats/min. At the initial stage of the arousal, while body temperature remains still low (9-10 degrees C), the heart rate may increase up to 160-200 beats/min. At this stage, practically all electrophysiological parameters of the heart correspond to those in active animals. These results may indicate the ability of "cold" heart in arousing ground squirrels to operate as a normothermic organ and reveal certain role of the heart in body warming. Significant increase of the intensity of protein synthesis in cardiomyocytes together with periodic changes in protein composition of their membranes were found during arousal which may account for regulation of the level of metabolism in cells and for adaptation of the latter to different temperatures.

Animals↗
PubMed1987

[Ultrastructural organization of cardiomyocyte sarcolemma in hibernating animals].

It was shown by electron microscopy that a highly convoluted sarcolemma, its numerous invaginations, well developed T-system contacting mainly with myofibrillar mitochondria and Z-zones were characteristic of cardiomyocytes of hibernants. In these cells lipid inclusions amounted as much as 3-4% of the cytoplasm. Cardiomyocytes of the arousing ground squirrels often revealed a complex of structures in the perinuclear area, responsible for protein synthesis and vesicle formation. Along with it the number of vesicles, including delineated ones, the majority of whom are contacting the sarcolemma, were manifested in the cell near-membrane area. A possible mechanism of cardiomyocyte plasma membrane rearrangements in ground squirrels and of alteration of their properties at the arousal, through a gradual replacement of plasma membrane material for the cytoplasmic vesicle bilayer, is discussed.

Animals↗
PubMedDate not supplied

[Homocarnosine levels in repeated hypothermia and hibernation].

Compulsory cooling of rats (20 degrees) and susliks (20 degrees-10 degrees) leads to a considerable decrease of homocarnosine in cerebral hemispheres in midbrain and diencephalon and cerebellum. When hypothermia is repeated 4 or 7 times (in every 24 h) a more considerable decrease in the homocarnosine quantity in the rat brain takes place and it is not normalized after self-warming of the organism. After 11-12-fold hypothermia, when a certain adaptation of animals to cooling is developed, the second increase of homocarnosine content with subsequent normalization of its level in great cerebral hemispheres and in cerebellum at self-warming is observed. In dynamics of the hibernation (1, 7 and 30 days) either preservation of normothermal level or a certain increase of the homocarnosine content in all areas of the suslik brain under examination is observed.

Animals↗
PubMed1985

[Ultrastructural study of the Sertoli cell in the seminiferous tubules of a hibernating animal, Eliomys quercinus L.), living in different lighting conditions].

The ultrastructure of the Sertoli cell studied in sexually active control animals during May-June and experimental animals sexually activated by light in winter, presents the commonly described ramified aspect with an infolded nucleus, well developed Golgi complexes, rough and smooth endoplasmic reticulum, numerous microfilaments, few liposomes and lysosomal formations; In the regressed testes of hibernating animals or blinded spring animals, the Sertoli cells are more round shaped with a significant increase in number and size of liposomes, lysosomes and various necrotic bodies. These morphological changes may be in favour of the possibility of a synchronization of the function of the Sertoli cell with the spermatogenic cycle to coordinate locally the proliferation and maturation of the germ cell.

Animals↗
PubMed1986

[Effect of serotonin on thermoregulation in normothermic hibernators and during arousal from deep hypothermia].

Serotonin, intraperitoneally injected (10 mg/kg) to arousing from hibernation ground squirrels, blocked the increase of body temperature and shivering thermogenesis and decreased O2 consumption. Serotonin administered to normothermic active animals also decreased body temperature and O2 consumption. However, compensative increase of muscle electrical activity in response to considerable decrease of the body temperature was not observed. Serotonin is suggested to take part in the control of body temperature set-point.

Animals↗
PubMed1979

Similarity in the number of lifespan heartbeats among non-hibernating homeothermic animals.

An investigation was made of the available data on heart rates and maximum lifespan of a number of vertebrates from a variety of sources; only data pertinent to resting adult non-anesthesized homeothermic mammals and birds in a state of thermal neutrality were subsequently analyzed. All known hibernators were excluded because of their extreme, and largely unknown, range of heartbeat from season to season. Plots of heart rate (beats per minute) against reciprocal of lifespan in years showed surprisingly good fits (r = +0.90 for mammals and r = +0.64 for birds). Computation of the total number of heartbeats in the maximum recorded lifespans of the mammalian and avian species involved in this study showed that the mean cumulative heartbeat number for 31 mammalian species was 100 +/- 8 S.E.M. x 10(7) beats and for 23 avian species was 326 +/- 22 S.E.M. x 10(7) beats. This paper documents this analysis, which supports the concept of a close similarity in lifespan heartbeats among mammalian species and among avian species.

Animals↗
PubMedDate not supplied

[Effect of hypothermia on the ammonia-glutamine-glutamic acid system in ground squirrels after hibernation].

The effect of forced cooling was studied as applied to the contents of ammonia, glutamine, glutaminic, asparaginic and alpha-amino butyric acids in the brain of sousliks woken-from hibernation. The cooling of the woken sousliks to the body temperature of 30, 20 and 25 degrees C decreased to some extent the ammonia content in the brain. A deeper hypothermia (10 degrees C) causes its 60,4% decrease as compared to the ammonia amount in woken animals. The cooling of the animals to 30, 25, 20 and 10 degrees C considerably decreases the contents of glutamine, glutaminic acid and GABA in the brain tissue.

Acclimatization↗
PubMed1978

[Histofluorescence study of epiphyseal monoamines in the garden dormouse (Eliomys quercinus L.) during various experimental conditions in hibernation period (author's transl)].

During the hibernation period, the epiphyseal catecholamine charge is well detected in the garden dormouse; it appears more important in darkened animals at 22 degrees C and much less in animals under continuous lighting. Serotoninergic elements have only been shown in animals living under complete darkness. An important catecholaminergic and indolaminergic charge appears in sexually-hypoactive-animals; during ovarian activation after illumination a diminution (of this charge) is observed. In this species, an inverse relation exists between the importance of epiphyseal monoaminergic metabolism and the hypothalamic gonadostimulating catecholamine discharge.

Animals↗
PubMed1983

[Morphofunctional analysis of the chief (peptic) glandulocytes in the stomach of hibernating rodents].

Ultrastructure of the chief gastric gland cells has been studied in the ground squirrel (Cytellus erythrogenys Brandt) at various seasons of the year. When the ground squirrel is in the active state, the cells studied do not differ from those in other animals. During winter hibernation, their activity is inhibited. During first days of awakening, the activity of the chief cells increases; the protein-synthesizing apparatus, the Golgi complex become activated, secreating granules accumulate. At the same time, the greatest number of the destroing cellular elements and discharge of the residual bodies out of the activizing cells are observed. Restoration of the normal structure in the chief cells is completed by the end of the second week. No signs demonstrating transformation of additional cells into the chief ones are revealed. Non-differentiated cells in the ground squirrel fundal glands are widely distributed along the whole length of the glandular cervix and occur even in the upper parts of its body.

Animals↗
PubMed1984

[Effect of gamma-aminobutyric and gamma-hydroxybutyric acids on the arousal of susliks from hibernation].

Experiments on male red-cheeked sousliks were made to examine the effects of substances interfering with different stages of GABA shunt on the animals' awakening assessed from the times of formation of the orthostatic reflex, the time course of rectal temperature, and the moment of the occurrence of active movements. The substances reducing (thiosemicarbazide) GABA content and elevating it (amino-oxyacetic acid) in the cerebral tissue have no effect on the above-indicated parameters of awakening. Meanwhile, p-dipropyl acetate (depakin) provokes a distinct dose-dependent increase in the time required for the recovery of the orthostatic reflex and transition to an active state. Sodium gamma-hydroxybutyric acid (GHBA) produces an analogous but more pronounced action. Both the drugs exhibit this effect when given even in low doses, in which they do not inhibit the thermogenesis. This evidence combined with the reported data on high GHBA concentration in brown fat suggests that GHBA may play a specific role in the mechanisms of hibernation.

Aminooxyacetic Acid↗
PubMed1978

Plasma glucose and insulin in the hibernating hedgehog.

Plasma glucose and insulin have been studied during lethargy and spontaneous arousal of hibernating hedgehogs. During lethargy, plasma glucose and insulin were low and showed no variation. Glucose and insulin injections given during lethargy showed no effects on plasma insulin and glucose respectively but confirmed a very low plasma clearance of glucose and insulin. During spontaneous arousal, the increase in plasma insulin occured before the increase in blood glucose and at about the time that utilization of blood glucose was restored.

Animals↗