scholarly journals Effects of hypothermia on energy metabolism in rat and Richardson’s ground squirrel hearts

1997 ◽  
Vol 82 (4) ◽  
pp. 1210-1218 ◽  
Author(s):  
Darrell D. Belke ◽  
Lawrence C. H. Wang ◽  
Gary D. Lopaschuk
Keyword(s):  
Energy Metabolism ◽  
Functional Recovery ◽  
Ground Squirrel ◽  
Ground Squirrels ◽  
General Effect ◽  
Energy Substrate ◽  
Substrate Metabolism ◽  
Hypothermic Perfusion ◽  
Rat Hearts ◽  
The Difference

Belke, Darrell D., Lawrence C. H. Wang, and Gary D. Lopaschuk. Effects of hypothermia on energy metabolism in rat and Richardson’s ground squirrel hearts. J. Appl. Physiol. 82(4): 1210–1218, 1997.—Glycolysis, glucose oxidation, palmitate oxidation, and cardiac function were measured in isolated working hearts from ground squirrels and rats subjected to a hypothermia-rewarming protocol. Hearts were perfused initially for 30 min at 37°C, followed by 2 h of hypothermic perfusion at 15°C, after which hearts were rewarmed to 37°C and further perfused for 30 min. Functional recovery in ground squirrel hearts was greater than in rat hearts after rewarming. Hypothermia-rewarming had a similar general effect on the various metabolic pathways in both species. Despite these similarities, total energy substrate metabolic rates were greater in rat than ground squirrel hearts during hypothermia despite a lower level of work being performed by the rat hearts, indicating that rat hearts are less efficient than ground squirrel hearts during hypothermia. After rewarming, energy substrate metabolism recovered completely in both species, although cardiac work remained depressed in rat hearts. The difference in functional recovery between rat and ground squirrel hearts after rewarming cannot be explained by general differences in energy substrate metabolism during hypothermia or after rewarming.

Isovolumetric performance of isolated ground squirrel and rat hearts at low temperature

1984 ◽  
Vol 247 (4) ◽  
pp. R722-R727 ◽  
Author(s):  
D. R. Caprette ◽  
J. B. Senturia
Keyword(s):  
Low Temperature ◽  
Ground Squirrel ◽  
Mechanical Performance ◽  
Cell Communication ◽  
Ventricular Myocardium ◽  
Ground Squirrels ◽  
Rat Hearts ◽  
Pulsus Alternans ◽  
Rate Of Increase ◽  
Developed Pressure

The effects of low temperature on mechanical performance of the isolated left ventricles of the 13-lined ground squirrel (a hibernator) and the rat (a nonhibernator) were studied. In addition, low-temperature performance of hearts from summer-active, winter-hibernating, and winter-active ground squirrels were compared. By measuring pressure (P) generated against a balloon inserted into the left ventricle, maximum developed pressure (DP) and maximum rate of increase of P (peak dP/dt) were determined over a temperature range of 5–20 degrees C. The DP and dP/dt of the rat ventricle exhibited significantly greater reduction in magnitude at reduced temperature, compared with those of ground squirrel ventricle. Rat, but not ground squirrel, hearts exhibited arrhythmias of various kinds, including extra-systoles, tachycardia, pulsus alternans, and periods of asystole. Hearts from winter-active ground squirrels developed greater pressures than those from winter-hibernating and summer-active animals. This evidence suggests that disruption of cell communication in the nonhibernator ventricular myocardium plays an important role in the failure of the nonhibernator heart at low body temperatures. Contractility of the seasonal hibernator's heart is influenced by both season and hibernation itself, possibly through shifts in myocardial metabolism. However, seasonal adaptations appear not to be required to confer the special resistance of the seasonal hibernator's heart to the deleterious effects of low temperature.

Isoflurane Alters Energy Substrate Metabolism to Preserve Mechanical Function in Isolated Rat Hearts following Prolonged No-Flow Hypothermic Storage

2003 ◽  
Vol 98 (2) ◽  
pp. 379-386 ◽  
Author(s):  
Barry A. Finegan ◽  
Manoj Gandhi ◽  
Matthew R. Cohen ◽  
Donald Legatt ◽  
Alexander S. Clanachan
Keyword(s):  
Enhanced Recovery ◽  
Metabolic Effects ◽  
Mechanical Function ◽  
Cardioplegic Arrest ◽  
Channel Activation ◽  
Energy Substrate ◽  
Myocardial Glucose Metabolism ◽  
Substrate Metabolism ◽  
Rat Hearts

Background Isoflurane enhances mechanical function in hearts subject to normothermic global or regional ischemia. The authors examined the effectiveness of isoflurane in preserving mechanical function in hearts subjected to cardioplegic arrest and prolonged hypothermic no-flow storage. The role of isoflurane in altering myocardial glucose metabolism during storage and reperfusion during these conditions and the contribution of adenosine triphosphate-sensitive potassium (K(atp)) channel activation in mediating the functional and metabolic effects of isoflurane preconditioning was determined. Methods Isolated working rat hearts were subjected to cardioplegic arrest with St. Thomas' II solution, hypothermic no-flow storage for 8 h, and subsequent aerobic reperfusion. The consequences of isoflurane treatment were assessed during the following conditions: (1) isoflurane exposure before and during storage; (2) brief isoflurane exposure during early nonworking poststorage reperfusion; and (3) isoflurane preconditioning before storage. The selective mitochondrial and sarcolemmal K(atp) channel antagonists, 5-hydroxydecanoate and HMR 1098, respectively, were used to assess the role of K(atp) channel activation on glycogen consumption during storage in isoflurane-preconditioned hearts. Results Isoflurane enhanced recovery of mechanical function if present before and during storage. Isoflurane preconditioning was also protective. Isoflurane reduced glycogen consumption during storage under the aforementioned circumstances. Storage of isoflurane-preconditioned hearts in the presence of 5-hydroxydecanoate prevented the reduction in glycogen consumption during storage and abolished the beneficial effect of isoflurane preconditioning on recovery of mechanical function. Conclusions Isoflurane provides additive protection of hearts subject to cardioplegic arrest and prolonged hypothermic no-flow storage and favorably alters energy substrate metabolism by modulating glycolysis during ischemia. The effects of isoflurane preconditioning on glycolysis during hypothermic no-flow storage appears to be associated with activation of mitochondrial K(atp) channels.

scholarly journals Hibernation strategies and patterns in sympatric arctic species, the Alaska marmot and the arctic ground squirrel

2015 ◽  
Vol 97 (1) ◽  
pp. 135-144 ◽  
Author(s):  
Trixie N. Lee ◽  
Franziska Kohl ◽  
C. Loren Buck ◽  
Brian M. Barnes
Keyword(s):  
Ground Squirrel ◽  
Core Body Temperature ◽  
Ground Squirrels ◽  
The Arctic ◽  
Arctic Ground Squirrel ◽  
Slow Cooling ◽  
Ambient Temperatures ◽  
The Difference ◽  
Arctic Ground Squirrels ◽  
Core Body

Abstract We compared patterns of core body temperature ( Tb ) change, including inter-individual synchrony, in 2 free-living arctic hibernators that differ in size and sociality, the Alaska marmot ( Marmota broweri ) and the arctic ground squirrel ( Urocitellus parryii ). We report overwinter Tb changes from 3 to 4 marmots from the same hibernaculum in each of 3 years and from 7 ground squirrels that hibernated at 2 nearby burrow sites in 1 year. Very close synchrony in the timing of torpor and arousal cycles in Alaska marmots indicates social hibernation and thermoregulation, while lack of synchrony in arctic ground squirrels further confirms solitary hibernation. The mean duration between the first and last marmot measured within the group to initiate an arousal was 3.7±2.5h and to recool to 30°C during torpor entrance was 5.7±3.7h. The minimum Tb recorded in marmots was 0.6°C and in ground squirrels was −2.0°C. Marmots entering torpor displayed an interrupted pattern of Tb change defined by 2 distinct rates of cooling, early and late during entry, that differed by 21-fold. Ground squirrels cooled in a continuous pattern, initially 3-fold slower than marmots during rapid cooling but 4-fold faster during slow cooling. Both species must minimize energy expenditure to survive long arctic winters; our results suggest that Alaska marmots do this through social thermoregulation, while arctic ground squirrels decrease Tb below freezing to minimize the difference between body and ambient temperatures.

scholarly journals Menstrual Cycle Hormonal Changes and Energy Substrate Metabolism in Exercising Women: A Perspective

2021 ◽  
Vol 18 (19) ◽  
pp. 10024
Author(s):  
Anthony C. Hackney
Keyword(s):  
Energy Metabolism ◽  
Menstrual Cycle ◽  
Nutrient Utilization ◽  
Evidence Based ◽  
Hormonal Changes ◽  
Energy Substrate ◽  
Future Studies ◽  
Substrate Metabolism ◽  
Exercising Women ◽  
Research Studies

This article discusses the research supporting that the hormonal changes across the menstrual cycle phases affect a woman’s physiology during exercise, specifically addressing aspects of energy substrate metabolism and macro-nutrient utilization and oxidation. The overarching aim is to provide a perspective on what are the limitations of earlier research studies that have concluded such hormonal changes do not affect energy metabolism. Furthermore, suggestions are made concerning research approaches in future studies to increase the likelihood of providing evidence-based data in support of the perspective that menstrual cycle hormonal changes do affect energy metabolism in exercising women.

scholarly journals Effect of dietary protein on energy metabolism including protein synthesis in the spiny lobster Sagmariasus verreauxi

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shuangyao Wang ◽  
Chris G. Carter ◽  
Quinn P. Fitzgibbon ◽  
Basseer M. Codabaccus ◽  
Gregory G. Smith
Keyword(s):  
Protein Synthesis ◽  
Energy Metabolism ◽  
Dietary Protein ◽  
Spiny Lobster ◽  
Ammonia Excretion ◽  
Metabolic Energy ◽  
Whole Body ◽  
Body Protein ◽  
Energy Substrate ◽  
Sagmariasus Verreauxi

AbstractThis is the first study in an aquatic ectotherm to combine a stoichiometric bioenergetic approach with an endpoint stochastic model to explore dietary macronutrient content. The combination of measuring respiratory gas (O2 and CO2) exchange, nitrogenous (ammonia and urea) excretion, specific dynamic action (SDA), metabolic energy substrate use, and whole-body protein synthesis in spiny lobster, Sagmariasus verreauxi, was examined in relation to dietary protein. Three isoenergetic feeds were formulated with varying crude protein: 40%, 50% and 60%, corresponding to CP40, CP50 and CP60 treatments, respectively. Total CO2 and ammonia excretion, SDA magnitude and coefficient, and protein synthesis in the CP60 treatment were higher compared to the CP40 treatment. These differences demonstrate dietary protein influences post-prandial energy metabolism. Metabolic use of each major energy substrate varied at different post-prandial times, indicating suitable amounts of high-quality protein with major non-protein energy-yielding nutrients, lipid and carbohydrate, are critical for lobsters. The average contribution of protein oxidation was lowest in the CP50 treatment, suggesting mechanisms underlying the most efficient retention of dietary protein and suitable dietary inclusion. This study advances understanding of how deficient and surplus dietary protein affects energy metabolism and provides approaches for fine-scale feed evaluation to support sustainable aquaculture.

scholarly journals Regulation of Energy Substrate Metabolism in Endurance Exercise

2021 ◽  
Vol 18 (9) ◽  
pp. 4963
Author(s):  
Abdullah F. Alghannam ◽  
Mazen M. Ghaith ◽  
Maha H. Alhussain
Keyword(s):  
Fatty Acids ◽  
Exercise Intensity ◽  
Fat Metabolism ◽  
Glycogen Storage ◽  
Regulatory Mechanisms ◽  
Critical Importance ◽  
Energy Substrate ◽  
Substrate Metabolism ◽  
Atp Turnover ◽  
Energy Demands

The human body requires energy to function. Adenosine triphosphate (ATP) is the cellular currency for energy-requiring processes including mechanical work (i.e., exercise). ATP used by the cells is ultimately derived from the catabolism of energy substrate molecules—carbohydrates, fat, and protein. In prolonged moderate to high-intensity exercise, there is a delicate interplay between carbohydrate and fat metabolism, and this bioenergetic process is tightly regulated by numerous physiological, nutritional, and environmental factors such as exercise intensity and duration, body mass and feeding state. Carbohydrate metabolism is of critical importance during prolonged endurance-type exercise, reflecting the physiological need to regulate glucose homeostasis, assuring optimal glycogen storage, proper muscle fuelling, and delaying the onset of fatigue. Fat metabolism represents a sustainable source of energy to meet energy demands and preserve the ‘limited’ carbohydrate stores. Coordinated neural, hormonal and circulatory events occur during prolonged endurance-type exercise, facilitating the delivery of fatty acids from adipose tissue to the working muscle for oxidation. However, with increasing exercise intensity, fat oxidation declines and is unable to supply ATP at the rate of the exercise demand. Protein is considered a subsidiary source of energy supporting carbohydrates and fat metabolism, contributing to approximately 10% of total ATP turnover during prolonged endurance-type exercise. In this review we present an overview of substrate metabolism during prolonged endurance-type exercise and the regulatory mechanisms involved in ATP turnover to meet the energetic demands of exercise.

scholarly journals Neuromuscular Electrical Stimulation Improves Energy Substrate Metabolism and Survival in Mice With Acute Endotoxic Shock

Shock ◽  
2020 ◽  
Vol 53 (2) ◽  
pp. 236-241
Author(s):  
Takayuki Irahara ◽  
Norio Sato ◽  
Kosuke Otake ◽  
Satoru Murata ◽  
Kazuo Inoue ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Endotoxic Shock ◽  
Neuromuscular Electrical Stimulation ◽  
Energy Substrate ◽  
Substrate Metabolism

Temperature and the Regulation of Enzyme Activity in the Hibernator. Isoenzymes of Liver Pyruvate Kinase from the Hibernating and Non-hibernating Arctic Ground Squirrel

1974 ◽  
Vol 52 (10) ◽  
pp. 894-902 ◽  
Author(s):  
Hans W. Behrisch
Keyword(s):  
Molecular Weight ◽  
Pyruvate Kinase ◽  
Wide Temperature Range ◽  
Ground Squirrel ◽  
Energy Charge ◽  
High Energy ◽  
Ground Squirrels ◽  
The Arctic ◽  
Arctic Ground Squirrel ◽  
Temperature Range

Liver of the hibernating (H) Arctic ground squirrel (Citellus undulatus) contains a single species of pyruvate kinase (PyK) that is distinct from the single isoenzyme of pyK observed in the non-hibernating (NH) ground squirrel, which has been previously described (Behrisch &Johnson (1974) Can. J. Biochem. 52, 547–559). The H-PyK has a pI value of 5.7 and a molecular weight of 241 000 – 243 000. Affinity of the H-PyK for the substrates phosphoenolpyruvate (PEP) and ADP is not affected by changing temperature. It is argued that this stability of the apparent Km's for substrate over a wide temperature range permits the hibernator to take advantage of the Q10 effect in maintaining a low rate of the PyK reaction. Similarly, affinity of H-PyK for the allosteric activator fructose-1,6-phosphate (FDP) and the inhibitor ATP is also conspicuously independent of temperature, suggesting a fine stoichiometry in the relative concentrations of the regulatory ligands in control of H-PyK over a wide temperature range. Further, affinity of H-PyK for the inhibitor ATP is about three- to fourfold lower than that of the NH-PyK, a condition that would favor the maintenance of a high energy charge in the hibernating liver cell. ATP apparently inhibits PyK by causing a dissociation of the enzyme molecule into two "halves" of about 110 000 molecular weight each. This dissociation is offset and reversed by FDP. Removal of the ATP by dialysis does not of itself result in a reassociation of the PyK "halves"; FDP and/or the substrates are required for the two subunits of PyK to reassociate. As the apparent Ki of H-PyK for ATP is higher than that of NH-PyK, substantially higher concentrations of ATP are required to effect the dissociation of H-PyK. Similarly, elevated concentrations of FDP are required to offset the ATP-caused dissociation of the H-PyK.Hibernating Arctic ground squirrels that are preparing to emerge finally from the hibernating state already possess substantial activities of the NH-PyK isoenzyme. This suggests that the animal "anticipates" its transition from one metabolic state from another. On the basis of these data a formal mechanism is proposed for the regulation of liver PyK in the Arctic ground squirrel in both the non-hibernating and hibernating states.

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