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Results for “HIBERNATION, ARTIFICIAL”

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At least 523 records · Page 29Linked to original sources
PubMed1997

Variation in normalized isometric tetanic force of isolated fast-twitch muscle fibres of Rana temporaria.

The origin of the threefold variation found previously in isometric force normalized to cross-sectional area of single fast-twitch tibialis anterior muscle fibres of the frog Rana temporaria was studied by using (1) a strictly defined stimulus protocol, and (2) influencing the condition of the frog using artificial hibernation. Variation in normalized force was found to be influenced by the length of the rest period between tetani. After a long rest (> 6h), tetanic force production was less than for a tetanus produced after 1 h. The length of the rest period accounted for a factor of 1.24 of the total variation in normalized force. The condition of the frog also influenced normalized force production. Little variation in normalized force was observed between different fibres from the same animal, whereas a significant difference was found between animals. After artificial hibernation, force normalized to cross-sectional area remained unchanged, but force normalized to dry mass per unit length increased; the total variation increased from a factor of 1.37 to a factor of 1.64. Force normalized to muscle protein mass per unit length, however, was not affected by artificial hibernation. We conclude that variation in normalized tetanic force can be partly reduced by standardization of the stimulation protocol and normalization to protein content per unit length.

Animals↗
PubMedDate not supplied

[Amino acid transport and protein synthesis in ground squirrels during hibernation and artificial hypothermia].

The intensity of labelled leucine penetration from the blood-circulating system to the tissues and its incorporation into proteins of some organs of gophers have been studied under hibernation and hypothermia. It is shown that, in spite of the low temperature of the gopher body under hibernation, the intensity of amino acids transfer from the blood to the tissue was approximately the same as in active state. But the rate of proteins synthesis under hibernation considerably decreases though it is not completely stopped. Under artificial hypothermia of the mammals the transition of amino acids from the blood to the tissue is considerably hampered. Under these conditions the incorporation of labelled amino acids is completely stopped.

Amino Acids↗
PubMedDate not supplied

[Basis for indicators of acid-base status of blood and metabolic processes in rats under hibernation and under trivial analgesia for foreleg amputation].

The article deals with some data on investigation of the blood acid-base balance main blood indices and metabolic processes in the rats organism under the artificial hibernation and trivial anesthesia at the foreleg amputation. This model of the artificial hibernation was shown as capable to be promising the hard and complicated operative intrusions in the organism.

Acid-Base Equilibrium↗
PubMed1991

Cold entrainment of the annual cycle of ovarian activity in the lizard Lacerta vivipara: thermoperiodic rhythm versus hibernation.

A constant warm thermoperiod maintains ovarian quiescence in the lizard Lacerta vivipara, whereas a 4-month artificial hibernation rapidly induces synchronized vitellogenesis after transfer to warmth. The present study examined the possibility of a thermoperiodic regulation of the ovarian cycle and the formal properties of an internal temporal program. These questions were addressed using 24-hr thermoperiodic conditions that combined a long or a short thermophase (6 or 2 hr of basking) with a warm (19-21 degrees C), a cool (5-15 degrees C), or a cold (3-7 degrees C) cryophase. Lizards were exposed to the natural photocycle or to LD 12:12. Occurrence and timing of vitellogenesis completion were monitored using immunodetection of plasma vitellogenin and laparotomies. Cold remained stimulatory when given intermittently with a 24-hr periodicity. However, under long-thermophase conditions, lizards responded poorly to cool cryophases but fully to cold ones (72.7-100% vitellogenesis). Thus a certain amount of cold must be provided during each 24-hr cycle in order to be effective through the succession of thermocycles. Reduction of the daily heat input from 6 to 2 hr modulated the stimulating effects of cold cryophases: The median date for the beginning of vitellogenesis occurred 1 month earlier, but the number of responding females decreased from 100% to 40%. The thermoperiodic regulation of the ovarian cycle also relies upon a precise heat-cold balance per nycthemeral unit. This ensures the entrainment of an internal rhythm, since the timing of reproductive responses varies with the date of transfer from the inhibitory warm thermoperiod to the inducing thermoperiod (long thermophase, cold cryophase). At least half the females started vitellogenesis within 1-2 months after a late transfer (winter solstice) instead of 6 months after an early one (autumn equinox), and the median date for onset differed by 1 month between the two groups. However, autumn transfer was the only one to induce a group response in close agreement with the natural timing.

Animals↗
PubMedDate not supplied

[Seasonal changes in the structural-functional properties of erythrocyte membranes from Citellus undulatus].

The influence of hypothermic storage upon Citellus undulatus erythrocytes extracted during different functional state of the hibernator: hibernation, artificial awakening in winter and summer activity has been investigated. It has been revealed that the cells of the animals, which were in the state of deep hibernation, showed in vitro higher resistance of the systems providing ionic homeostasis (Na+/K+- and Ca(2+)-pompes and passive permeability) not only in comparison with the cells of non-hibernators but also in comparison with the cells of animals of the same species, which were in different functional states. Seasonal alterations of protein composition of ground squirrel erythrocyte membranes have been also investigated and ionic permeabilities of the monolamellar liposomes constructed from hibernator and non-hibernator erythrocyte membrane lipids have been compared. Results obtained have confirmed that the changes in membrane proteins took place during hibernation and these changes, probably, provided cold resistance to a more considerable extent than the changes of characteristics of lipid bilayer.

Animals↗
PubMed1994

Seasonal modulation of interferon response in spotted sousliks (Spermophilus suslicus).

Interferon production in spotted sousliks in different physiological states: in summer activity, summer torpor, winter hibernation and awaked from winter hibernation was studied. Three different interferon inducers: poly rI:rC complexed with DEAE-dextran, lipopolysaccharide from E. coli (LPS) and tilorone hydrochloride were used. In comparison with sousliks active in summer, the interferon levels in serum and different organs of sousliks in winter hibernation after induction with tilorone hydrochloride, LPS and poly rI:rC were significantly lower. Decreased interferon response was also observed in sousliks in summer torpor and awaked from winter hibernation. In contrast to hibernation, artificial acidosis induced by placing sousliks in the atmosphere with a high concentration of CO2 enhanced interferon production.

Animals↗