Ketone body metabolism in a ground squirrel during hibernation and fasting

1985 ◽  
Vol 249 (4) ◽  
pp. R462-R470 ◽  
Author(s):  
B. L. Krilowicz
Keyword(s):  
Energy Source ◽  
Glucose Uptake ◽  
Ground Squirrel ◽  
Ketone Body ◽  
Glucose Utilization ◽  
Ground Squirrels ◽  
Body Protein ◽  
Muscle Tissues ◽  
Spermophilus Beldingi

Hibernating Belding's ground squirrels (Spermophilus beldingi) are ketotic relative to fed nonhibernators. Muscles from torpid individuals, when incubated in media containing physiological concentrations of glucose and ketone, show reduced uptake of glucose in the presence of ketone. The magnitude of the reduction is dependent on ketone concentration and reaches 60% in heart and 100% in pectoralis at 1.4 mM ketone. Fasted squirrels are also ketotic. However, ketone does not reduce glucose uptake in muscles from fed or fasted animals. Glucose utilization by muscles decreases during a long-term fast, but the reduction is independent of ketone. Thus both a long-term fast and hibernation lead to changes in muscle tissues that decrease their reliance on glucose as an energy source. Ketosis leads to glucose sparing during hibernation, whereas muscle glucose utilization is decreased independently of ketone during a fast. The glucose sparing achieved in both hibernation and fasting leads to conservation of body protein, the major source of gluconeogenic precursors in fasting mammals.

scholarly journals Resistance of Erythrocytes of Hibernating Mammals to Loss of Potassium during Hibernation and during Cold Storage

1971 ◽  
Vol 58 (6) ◽  
pp. 620-633 ◽  
Author(s):  
S. L. Kimzey ◽  
J. S. Willis
Keyword(s):  
Ground Squirrel ◽  
Normal Values ◽  
Ground Squirrels ◽  
Storage Medium ◽  
Cold Adapted ◽  
Maximum Period ◽  
K Concentration

In two species of hibernators, hamsters and ground squirrels, erythrocytes were collected by heart puncture and the K content of the cells of hibernating individuals was compared with that of awake individuals. The K concentration of hamsters did not decline significantly during each bout of hibernation (maximum period of 5 days) but in long-term bouts in ground squirrels (i.e. more than 5 days) the K concentration of cells dropped significantly. When ground squirrels were allowed to rewarm the K content of cells rose toward normal values within a few hours. Erythrocytes of both hamsters and ground squirrels lose K more slowly than those of guinea pigs (nonhibernators) when stored in vitro for up to 10 days at 5°C. In ground squirrels the rate of loss of K during storage is the same as in vivo during hibernation, and stored cells taken from hibernating ground squirrels also lose K at the same rate. The rate of loss of K from guinea pig cells corresponded with that predicted from passive diffusion unopposed by transport. The actual rate of loss of K from ground squirrel cells was slower than such a predicted rate but corresponded with it when glucose was omitted from the storage medium or ouabain was added to it. Despite the slight loss of K that may occur in hibernation, therefore, the cells of hibernators are more cold adapted than those of a nonhibernating mammal, and this adaptation depends in part upon active transport.

Gluconeogenesis in arctic ground squirrels between periods of hibernation

1975 ◽  
Vol 228 (1) ◽  
pp. 325-330 ◽  
Author(s):  
W Galster ◽  
PR Morrison
Keyword(s):  
Energy Source ◽  
Fatty Acid ◽  
Protein Metabolism ◽  
Ground Squirrel ◽  
Ammonia Nitrogen ◽  
Ground Squirrels ◽  
The Arctic ◽  
Major Energy Source ◽  
Arctic Ground Squirrels ◽  
Gluconeogenic Substrate

The hibernation season in the arctic ground squirrel (Citellus undulatus) is broken into 8- to 18- day cycles by short homeothermal periods during which the carboydrate reserves depleted during hibernation are replenished. This study follows a number of metabolities in tissues and body fluids to assess the sources for reconstitution of the glucose reserves: lactate, urea, ammonia, free fatty acid, glycerol, triglyceride, and glucose in plasma; glycogen in liver and muscle; and urea and ammonia nitrogen in urine. Fat is the major energy source during both homeothermal and heterothermal periods, the contribution from glucose being limited to glycolysis. Reconstitution of glycogen is accomplished prior to reentry through maximal use of substrates from all sources including glycolysis, fat, and protein metabolism. Of the new gluconeogenic substrate, one-fourth is supplied from protein and three-fourths from fat.

Adaptations for hibernation in the depot fats of a ground squirrel (Spermophilus beldingi)

1991 ◽  
Vol 69 (11) ◽  
pp. 2707-2711 ◽  
Author(s):  
Craig L. Frank
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Melting Point ◽  
Ground Squirrel ◽  
Unsaturated Fatty Acids ◽  
Ground Squirrels ◽  
Body Temperatures ◽  
Melting Points ◽  
Spermophilus Beldingi ◽  
Free Ranging

Ground squirrels are small herbivores that hibernate during winter. The ecological–nutritional limitations on hibernation are virtually unknown, but one constraint may be the melting point of stored fat. Lipids must be fluid to be metabolizable, and body temperatures maintained during hibernation are usually 30 °C below the melting point of typical mammalian fats. Fats containing greater amounts of unsaturated fatty acids, however, have correspondingly lower melting points. White adipose tissue was sampled from free-ranging Belding's ground squirrels, Spermophilus beldingi, during both the summer and fall. The lipids were twice as unsaturated as those of other rodent species, most of the increased unsaturation being due to the accumulation of plant-produced polyunsaturated fatty acids derived from the animals' diet. The melting points of S. beldingi fats were consequently 25 °C lower than those of other mammals. These results suggest that ground squirrels may depend upon their plant diet for the polyunsaturates necessary to produce the lipids with low melting points that are needed for hibernation.

Blood pressure responses as an indicator of the anesthetic level in ground squirrels

1976 ◽  
Vol 40 (6) ◽  
pp. 977-981 ◽  
Author(s):  
M. Gur ◽  
R. L. Purple
Keyword(s):  
Arterial Pressure ◽  
Ground Squirrel ◽  
Artificial Respiration ◽  
Ground Squirrels ◽  
Halothane Anesthesia ◽  
Small Perturbations ◽  
Halothane Concentration ◽  
Long Term Experiments ◽  
Blood Pressure Responses

In many experiments in visual physiology which employ halothane anesthesia, it is difficult to judge accurately an animal's anesthetic state, particularly so because of the necessity for paralysis and artificial respiration. For the ground squirrel (Citellus tridecemlineatus and C. mexicanus), we find that measures of arterial pressure response to a noxious stimulus combined with mean arterial pressure allow for an accurate division of halothane anesthetic state into five stages. All five stages are identified and are the same regardless of whether the animal is unparalyzed or is paralyzed and artificially respired. Use of these measures in long-term experiments allows for recognition of and adjustment for small perturbations of anesthetic state that may occur even though inhaled halothane concentration remains constant.

Action of epinephrine on muscle glucose uptake depending on Ca++ and phosphate

1965 ◽  
Vol 209 (2) ◽  
pp. 359-364 ◽  
Author(s):  
Michio Ui
Keyword(s):  
Glucose Metabolism ◽  
Glucose Uptake ◽  
Inorganic Phosphate ◽  
Glucose Utilization ◽  
Rat Diaphragm ◽  
Muscle Tissues ◽  
Ph Level ◽  
Diaphragm In Vitro

Studies have been made of the involvement of inorganic phosphate (Pi) and Ca++ in the mechanism by which epinephrine-induced inhibition of muscle glucose utilization was abolished during either alkalosis in vivo or incubation of the isolated rat diaphragm in vitro at a higher pH level. An increase in the concentration of Pi in muscle tissues was closely associated with prevention of the inhibitory action of epinephrine on glucose uptake. The interrelationship of Ca++ and Pi in aqueous solutions, and the additional observations that glucose uptake by rat diaphragm was accelerated in anaerobiosis only in the absence of Ca++, indicate a significance of Ca++ in muscle glucose metabolism. Assay of hexokinase activity in cell-free muscle preparations revealed that the inhibition of the enzyme activity by glucose 6-phosphate was profoundly influenced by the presence of Ca++ and Pi and was dependent on the concentration of ATP. It is suggested that Ca++ may provide the primary point of influence of epinephrine on glucose metabolism of the muscle.

Ketone bodies: a source of energy during hibernation

1981 ◽  
Vol 59 (5) ◽  
pp. 754-760 ◽  
Author(s):  
Josefine C. Rauch ◽  
Hans W. Behrisch
Keyword(s):  
Ground Squirrel ◽  
Ketone Body ◽  
Ketone Bodies ◽  
Ground Squirrels ◽  
Brown Fat ◽  
Arctic Ground Squirrel ◽  
Tissue Concentrations ◽  
Brown Adipose ◽  
Spermophilus Undulatus ◽  
Arctic Ground Squirrels

Tissue concentrations of acetoacetate and β-hydroxybutyrate (ketone bodies) were determined for the blood, liver, caecum, heart, and axillary brown fat, from nonhibernating and hibernating arctic ground squirrels, Spermophilus undulatus, in late spring and during winter, respectively. AcetylCoA and acetoacetylCoA concentrations were measured in the liver, heart, and brown adipose tissue.Except that the concentration of acetylCoA remained unchanged in the liver, all tissues investigated showed elevated concentrations of acetylCoA, acetoacetylCoA, and ketone bodies during the hibernating state. From the increased concentrations of acetoacetate and β-hydroxybutyrate it was deduced that active ketone body metabolism occurs in the hibernating arctic ground squirrel, and that during hibernation, ketone bodies are probably an important source of energy.

Use of visual cues in foraging by a diurnal herbivore, Belding's ground squirrel

1998 ◽  
Vol 76 (9) ◽  
pp. 1766-1770 ◽  
Author(s):  
Richard D Duncan ◽  
Stephen H Jenkins
Keyword(s):  
Ground Squirrel ◽  
Visual Cues ◽  
Growing Season ◽  
Ground Squirrels ◽  
Foraging Efficiency ◽  
Natural Conditions ◽  
Spermophilus Beldingi ◽  
Bait Stations

Ground squirrels' vision has been fairly well characterized, but whether they actually use vision in foraging has not been demonstrated. Belding's ground squirrels (Spermophilus beldingi) were allowed to forage under natural conditions for experimental bait stations to test the hypothesis that they can learn to use visual cues to forage more efficiently. Bait stations with visual cues were more likely to be found, and were found more quickly, than controls. Bait stations in taller and (or) denser vegetation were less likely to be found, suggesting that the value of visual cues may change during the growing season. Visual cues can be used to increase foraging efficiency, but other cues are probably used as well.

scholarly journals Testosterone activates glucose metabolism through AMPK and androgen signaling in cardiomyocyte hypertrophy

2021 ◽  
Vol 54 (1) ◽  
Author(s):  
Mayarling Francisca Troncoso ◽  
Mario Pavez ◽  
Carlos Wilson ◽  
Daniel Lagos ◽  
Javier Duran ◽  
...  
Keyword(s):  
Glucose Metabolism ◽  
Cardiac Hypertrophy ◽  
Glucose Uptake ◽  
Male Rats ◽  
Cardiomyocyte Hypertrophy ◽  
Mrna Levels ◽  
Elevated Glucose ◽  
Amp Activated Protein Kinase ◽  
Cultured Cardiomyocytes

Abstract Background Testosterone regulates nutrient and energy balance to maintain protein synthesis and metabolism in cardiomyocytes, but supraphysiological concentrations induce cardiac hypertrophy. Previously, we determined that testosterone increased glucose uptake—via AMP-activated protein kinase (AMPK)—after acute treatment in cardiomyocytes. However, whether elevated glucose uptake is involved in long-term changes of glucose metabolism or is required during cardiomyocyte growth remained unknown. In this study, we hypothesized that glucose uptake and glycolysis increase in testosterone-treated cardiomyocytes through AMPK and androgen receptor (AR). Methods Cultured cardiomyocytes were stimulated with 100 nM testosterone for 24 h, and hypertrophy was verified by increased cell size and mRNA levels of β-myosin heavy chain (β-mhc). Glucose uptake was assessed by 2-NBDG. Glycolysis and glycolytic capacity were determined by measuring extracellular acidification rate (ECAR). Results Testosterone induced cardiomyocyte hypertrophy that was accompanied by increased glucose uptake, glycolysis enhancement and upregulated mRNA expression of hexokinase 2. In addition, testosterone increased AMPK phosphorylation (Thr172), while inhibition of both AMPK and AR blocked glycolysis and cardiomyocyte hypertrophy induced by testosterone. Moreover, testosterone supplementation in adult male rats by 5 weeks induced cardiac hypertrophy and upregulated β-mhc, Hk2 and Pfk2 mRNA levels. Conclusion These results indicate that testosterone stimulates glucose metabolism by activation of AMPK and AR signaling which are critical to induce cardiomyocyte hypertrophy.

scholarly journals β-Sitosterol-D-Glucopyranoside Mimics Estrogenic Properties and Stimulates Glucose Utilization in Skeletal Muscle Cells

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3129
Author(s):  
Jyotsana Pandey ◽  
Kapil Dev ◽  
Sourav Chattopadhyay ◽  
Sleman Kadan ◽  
Tanuj Sharma ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Glucose Utilization ◽  
Diabetes Management ◽  
Expression System ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Cell Periphery ◽  
Glut4 Translocation ◽  
In Silico Docking

Estrogenic molecules have been reported to regulate glucose homeostasis and may be beneficial for diabetes management. Here, we investigated the estrogenic effect of β-sitosterol-3-O-D-glucopyranoside (BSD), isolated from the fruits of Cupressus sempervirens and monitored its ability to regulate glucose utilization in skeletal muscle cells. BSD stimulated ERE-mediated luciferase activity in both ERα and ERβ-ERE luc expression system with greater response through ERβ in HEK-293T cells, and induced the expression of estrogen-regulated genes in estrogen responsive MCF-7 cells. In silico docking and molecular interaction studies revealed the affinity and interaction of BSD with ERβ through hydrophobic interaction and hydrogen bond pairing. Furthermore, prolonged exposure of L6-GLUT4myc myotubes to BSD raised the glucose uptake under basal conditions without affecting the insulin-stimulated glucose uptake, the effect associated with enhanced translocation of GLUT4 to the cell periphery. The BSD-mediated biological response to increase GLUT4 translocation was obliterated by PI-3-K inhibitor wortmannin, and BSD significantly increased the phosphorylation of AKT (Ser-473). Moreover, BSD-induced GLUT4 translocation was prevented in the presence of fulvestrant. Our findings reveal the estrogenic activity of BSD to stimulate glucose utilization in skeletal muscle cells via PI-3K/AKT-dependent mechanism.

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