glycogen and Fever

The intake of fluid and CHO offers benefits to the performance of a number of sports events and exercise activities. The effects of dehydration on performance are now well known, with the penalties ranging from subtle, but often important, decrements in performance at low levels of fluid deficit to the severe health risks associated with substantial fluid losses during exercise in the heat. Although evidence of the beneficial effects of CHO intake during exercise have existed for over 70 years, sports scientists are still to discover all the situations in which benefits occur and to explain the mechanisms involved. Optimal strategies for CHO and fluid intake during exercise are yet to be fine-tuned, and ultimately will be determined by practical issues such as the opportunity to eat or drink during an event, and gastrointestinal comfort.

Topics: Dehydration; Dietary Carbohydrates; Drinking; Exercise; Fever; Glycogen; Humans; Physical Endurance; Taste; Water-Electrolyte Balance

The development of fatigue during exercise and the subsequent onset of exhaustion occur earlier in the heat than in cooler environments. The underlying mechanisms responsible for the premature development of fatigue in the heat have yet to be clearly identified. However, the proposed mechanisms include metabolic, cardiovascular and central nervous system perturbations, together with an elevated core temperature. Fluid ingestion is one of three strategies that have been shown to be successful in enhancing the performance of endurance exercise in the heat, with the other interventions being precooling and acclimatization. However, like the development of fatigue in the heat, the mechanisms by which fluid ingestion allows for improved exercise performance remain unclear. We propose that fluid ingestion enhances exercise performance in the heat by increasing the heat storage capacity of the body. We suggest that the thermoregulatory, metabolic and cardiovascular alterations that occur as a result of this increased heat storage capacity contribute to performance enhancement when fluid is ingested during exercise heat stress.

Topics: Body Fluids; Body Temperature Regulation; Dehydration; Energy Metabolism; Exercise; Female; Fever; Fluid Therapy; Glycogen; Humans; Male; Muscle Fatigue; Water-Electrolyte Balance

We determined if dehydration alone or in combination with hyperthermia accelerates muscle glycogen use during intense exercise. Seven endurance-trained cyclists (VO2max  = 54.4 ± 1.05 mL/kg/min) dehydrated 4.6% of body mass (BM) during exercise in the heat (150 min at 33 ± 1 °C, 25 ± 2% humidity). During recovery (4 h), subjects remained dehydrated (HYPO trial) or recovered all fluid losses (REH trials). Finally, subjects exercised intensely (75% VO2max ) for 40 min in a neutral (25 ± 1 °C; HYPO and REH trials) or in a hot environment (36 ± 1 °C; REHHOT ). Before the final exercise bout vastus lateralis glycogen concentration was similar in all three trials (434 ± 57 mmol/kg of dry muscle (dm)) but muscle water content was lower in the HYPO (357 ± 14 mL/100 g dm) than in REH trials (389 ± 25 and 386 ± 25 mL/100 g dm; P < 0.05). After 40 min of intense exercise, intestinal temperature was similar between the HYPO and REHHOT trials (39.2 ± 0.5 and 39.2 ± 0.4 °C, respectively) and glycogen use was similar (172 ± 86 and 185 ± 97 mmol/kg dm, respectively) despite large differences in muscle water content. In contrast, during REH, intestinal temperature (38.5 ± 0.4 °C) and glycogen use (117 ± 52 mmol/kg dm) were significantly lower than during HYPO and REHHOT . Our data suggest that hyperthermia stimulates glycogen use during intense exercise while muscle water deficit has a minor role.

Topics: Adult; Bicycling; Biomarkers; Cross-Over Studies; Dehydration; Exercise; Fever; Glycogen; Hot Temperature; Humans; Quadriceps Muscle; Water-Electrolyte Balance

Topics: Animals; Cardiomegaly; Crosses, Genetic; Enzyme-Linked Immunosorbent Assay; Fever; Gene Expression Profiling; Glycogen; Heart Rate; Hypothyroidism; Lipolysis; Liver; Male; Mental Retardation, X-Linked; Mice; Mice, Inbred C57BL; Mice, Knockout; Monocarboxylic Acid Transporters; Muscle Hypotonia; Muscular Atrophy; Phenotype; Telemetry; Thermogenesis; Thermography; Thyroid Hormones; Time Factors; Triiodothyronine

Developmental changes in ovine myocardial glucose transporters and insulin signaling following hyperthermia-induced intrauterine fetal growth restriction (IUGR) were the focus of our study. Our objective was to test the hypothesis that the fetal ovine myocardium adapts during an IUGR gestation by increasing glucose transporter protein expression, plasma membrane-bound glucose transporter protein concentrations, and insulin signal transduction protein concentrations. Growth measurements and whole heart tissue were obtained at 55 days gestational age (dGA), 90 dGA, and 135 dGA (term = 145 dGA) in fetuses from control (C) and hyperthermic (HT) pregnant sheep. Additionally, in 135 dGA animals, arterial blood was obtained and Doppler ultrasound was used to determine umbilical artery systolic (S) and diastolic (D) flow velocity waveform profiles to calculate pulsatility (S - D/mean) and resistance (S - D/S) indices. Myocardial Glut-1, Glut-4, insulin signal transduction proteins involved in Glut-4 translocation, and glycogen content were measured. Compared to age-matched controls, HT 90-dGA fetal body weights and HT 135-dGA fetal weights and gross heart weights were lower. Heart weights as a percent of body weights were similar between C and HT sheep at 135 dGA. HT 135-dGA animals had (i) lower fetal arterial plasma glucose and insulin concentrations, (ii) lower arterial blood oxygen content and higher plasma lactate concentrations, (iii) higher myocardial Glut-4 plasma membrane (PM) protein and insulin receptor beta protein (IRbeta ) concentrations, (iv) higher myocardial glycogen content, and (v) higher umbilical artery Doppler pulsatility and resistance indices. The HT ovine fetal myocardium adapts to reduced circulating glucose and insulin concentrations by increasing plasma membrane Glut-4 and IRbeta protein concentrations. The increased myocardial Glut-4 PM and IRbeta protein concentrations likely contribute to or increase the intracellular delivery of glucose and, together with the increased lactate concentrations, enhance glycogen synthesis, which allows for maintained myocardial growth commensurate with fetal body growth.

Topics: Animals; Body Weight; Female; Fetal Growth Retardation; Fever; Gestational Age; Glucose; Glucose Transporter Type 1; Glucose Transporter Type 4; Glycogen; Insulin; Insulin Receptor Substrate Proteins; Intracellular Signaling Peptides and Proteins; Myocardium; Organ Size; Phosphatidylinositol 3-Kinases; Phosphoproteins; Pregnancy; Proto-Oncogene Proteins c-akt; Receptor, Insulin; Sheep, Domestic; Signal Transduction

A 14-month-old girl was hospitalized due to repeated hyper-creatine kinase (CK)-emia during pyrexia. Mild hypotonia was observed, but other physical and neurological findings were unremarkable. The serum CK level was normal at rest or normothermia. Open muscle biopsy was performed on the rectus femoris, and showed glycogen storage and complete lack of phosphorylase activity histochemically and biochemically, establishing the diagnosis of McArdle disease. The diagnosis of McArdle disease in early infancy is uncommon. Until this study there have been no reports of clinical symptoms or muscle biopsy findings for McArdle disease in early childhood. This disease must be considered when transient hyper-CKemia is observed in infants, even if glycogen storage is unremarkable as compared with adult cases.

Topics: Biopsy; Creatine Kinase; Female; Fever; Glycogen; Glycogen Phosphorylase; Glycogen Storage Disease Type V; Humans; Immunohistochemistry; Infant; Microscopy, Electron; Muscle, Skeletal

Oxidative and/or bioenergetic stress is thought to contribute to the mechanism of neurotoxicity of amphetamine derivatives, e.g., 3,4-methylenedioxymethamphetamine (MDMA). In the present study, the effect of MDMA on brain energy regulation was investigated by examining the effect of MDMA on brain glycogen and glucose. A single injection of MDMA (10-40 mg/kg, s.c.) produced a dose-dependent decrease (40%) in brain glycogen, which persisted for at least 1 h. MDMA (10 and 40 mg/kg, s.c.) also produced a significant and sustained increase in the extracellular concentration of glucose in the striatum. Subjecting rats to a cool ambient temperature of 17 degrees C significantly attenuated MDMA-induced hyperthermia and glycogenolysis. MDMA-induced glycogenolysis also was prevented by treatment of rats with the 5-hydroxytryptamine(2) (5-HT(2)) antagonists 6-methyl-1-(1-methylethyl)-ergoline-8 beta-carboxylic acid 2-hydroxy-1 methylprophyl ester maleate (LY-53,857; 3 mg/kg i.p.), desipramine (10 mg/kg i.p.), and iprindole (10 mg/kg i.p.). LY-53,857 also attenuated the MDMA-induced increase in the extracellular concentration of glucose as well as MDMA-induced hyperthermia. Amphetamine analogs (e.g., methamphetamine and parachloroamphetamine) that produce hyperthermia also produced glycogenolysis, whereas fenfluramine, which does not produce hyperthermia, did not alter brain glycogen content. These results support the conclusion that MDMA induces glycogenolysis and that the process involves 5-HT(2) receptor activation. These results are supportive of the view that MDMA promotes energy dysregulation and that hyperthermia may play an important role in MDMA-induced alterations in cellular energetics.

Topics: Animals; Body Temperature; Brain Chemistry; Corpus Striatum; Dose-Response Relationship, Drug; Extracellular Space; Fever; Glucose; Glycogen; Hallucinogens; Male; Microdialysis; N-Methyl-3,4-methylenedioxyamphetamine; Rats; Rats, Sprague-Dawley; Receptors, Serotonin; Serotonin Antagonists

1. The present study examined whether reductions in muscle blood flow with exercise-induced dehydration would reduce substrate delivery and metabolite and heat removal to and from active skeletal muscles during prolonged exercise in the heat. A second aim was to examine the effects of dehydration on fuel utilisation across the exercising leg and identify factors related to fatigue. 2. Seven cyclists performed two cycle ergometer exercise trials in the heat (35 C; 61 +/- 2 % of maximal oxygen consumption rate, VO2,max), separated by 1 week. During the first trial (dehydration, DE), they cycled until volitional exhaustion (135 +/- 4 min, mean +/- s.e.m.), while developing progressive DE and hyperthermia (3.9 +/- 0.3 % body weight loss and 39.7 +/- 0.2 C oesophageal temperature, Toes). On the second trial (control), they cycled for the same period of time maintaining euhydration by ingesting fluids and stabilising Toes at 38.2 +/- 0.1 degrees C. 3. After 20 min of exercise in both trials, leg blood flow (LBF) and leg exchange of lactate, glucose, free fatty acids (FFA) and glycerol were similar. During the 20 to 135 +/- 4 min period of exercise, LBF declined significantly in DE but tended to increase in control. Therefore, after 120 and 135 +/- 4 min of DE, LBF was 0.6 +/- 0.2 and 1.0 +/- 0.3 l min-1 lower (P < 0.05), respectively, compared with control. 4. The lower LBF after 2 h in DE did not alter glucose or FFA delivery compared with control. However, DE resulted in lower (P < 0.05) net FFA uptake and higher (P < 0.05) muscle glycogen utilisation (45 %), muscle lactate accumulation (4.6-fold) and net lactate release (52 %), without altering net glycerol release or net glucose uptake. 5. In both trials, the mean convective heat transfer from the exercising legs to the body core ranged from 6.3 +/- 1.7 to 7.2 +/- 1.3 kJ min-1, thereby accounting for 35-40 % of the estimated rate of heat production ( approximately 18 kJ min-1). 6. At exhaustion in DE, blood lactate values were low whereas blood glucose and muscle glycogen levels were still high. Exhaustion coincided with high body temperature ( approximately 40 C). 7. In conclusion, the present results demonstrate that reductions in exercising muscle blood flow with dehydration do not impair either the delivery of glucose and FFA or the removal of lactate during moderately intense prolonged exercise in the heat. However, dehydration during exercise in the heat elevates carbohydrate oxidation and lactate pro

Topics: Adult; Blood Glucose; Body Temperature; Carbon Dioxide; Dehydration; Epinephrine; Exercise; Exercise Test; Fatigue; Fatty Acids, Nonesterified; Fever; Glucagon; Glycerol; Glycogen; Humans; Insulin; Lactic Acid; Male; Muscle, Skeletal; Oxygen Consumption; Phosphocreatine; Regional Blood Flow; Thermodynamics

Experiments have shown that Dachengqi Decoction can inhibit the activity of G-germs which commonly grow in the intestinal tract, inactivate the endotoxin directly in vitro, reduce the amplitude of fever caused by endotoxin injected intravenously, promote the gastric secretion and gastric retaining in rats, and increase the level of glycogen in liver. It also has some other effects. All these actions contribute to the explanation on the efficacy of Dachengqi Decoction to purge off the internal heat.

Topics: Animals; Bile; Drugs, Chinese Herbal; Endotoxins; Enterobacteriaceae; Female; Fever; Gastric Juice; Glycogen; Leukocyte Count; Limulus Test; Liver; Male; Microbial Sensitivity Tests; Rabbits; Rats; Rats, Wistar

Changes in brain protein synthesis activity, and in brain levels of glucose, glycogen, and several high-energy phosphate metabolites, were evaluated under conditions of amphetamine-induced hyperthermia in mice. Protein synthesis showed a striking dependence on rectal temperature (TR), falling abruptly at TR above 40 degrees C. A similar result was obtained following direct heating of the animals. Protein synthesis activity in liver showed the same temperature dependence observed for brain. Increased synthesis of a protein with characteristics of the major mammalian stress protein, hsp 70, was demonstrated in both brain and liver following amphetamine administration. Brain protein synthesis showed significant recovery within 2 h after amphetamine administration whereas that of liver remained below 30% of control activity, suggesting significant temporal and quantitative differences in the response of individual tissues to elevated temperatures. Brain glycogen levels after amphetamine administration were significantly lower under conditions of ambient temperature which resulted in more severe drug-induced hyperthermia but did not correlate as strikingly as protein synthesis with the temperatures of individual animals. Brain glycogen also fell in animals whose temperatures were increased by brief exposure at high ambient temperature. Brain glucose levels did not consistently change with hyperthermia. Slight decreases in high-energy phosphates with increasing TR were likely the result of fixation artifact. These results demonstrate the fundamental role of hyperthermia in the reduction of protein synthesis in brain and other tissues by amphetamine, and suggest that temperature also constitutes a significant source of variability in the effects of this drug on brain energy metabolism, in particular glycogenolysis.

Topics: Adenosine Triphosphate; Amphetamine; Animals; Body Temperature; Brain; Energy Metabolism; Fever; Glycogen; Guanosine Triphosphate; Kinetics; Male; Mice; Nerve Tissue Proteins

The muscle contents of high-energy phosphates and their derivatives [ATP, ADP, AMP, creatine phosphate (CrP), and creatine], glycogen, some glycolytic intermediates, pyruvate, and lactate were compared in 11 dogs performing prolonged heavy exercise until exhaustion (at ambient temperature 20.0 +/- 1.0 degrees C) without and with trunk cooling using ice packs. Without cooling, dogs were able to run for 57 +/- 8 min, and their rectal (Tre) and muscle (Tm) temperatures increased to 41.8 +/- 0.2 and 43.0 +/- 0.2 degrees C, respectively. Compared with noncooling, duration of exercise with cooling was longer by approximately 45% while Tre and Tm at the time corresponding to the end of exercise without cooling were lower by 1.1 +/- 0.2 and 1.2 +/- 0.2 degrees C, respectively. The muscle contents of high-energy phosphates (ATP + CrP) decreased less, the rate of glycogen depletion was lower, and the increases in the contents of AMP, pyruvate, and lactate as well as in the muscle-to-blood lactate ratio were smaller. The muscle content of lactate was positively correlated with Tm. The data indicate that with higher body temperature equilibrium between high-energy phosphate breakdown and resynthesis was shifted to the lower values of ATP and CrP and glycolysis was accelerated. The results suggest that hyperthermia developing during prolonged muscular work exerts an adverse effect on muscle metabolism that may be relevant to limitation of endurance.

Topics: Adenine Nucleotides; Animals; Blood Glucose; Body Temperature; Body Water; Dogs; Fever; Glucose; Glycogen; Lactates; Male; Muscles; Physical Endurance; Physical Exertion; Pyruvates

Peritoneal exudate was collected from rabbits 18 hr after ip injection of shellfish glycogen. The fluid was centrifuged and the peritoneal exudate supernatant (PES) retained for use in growth studies. The growth of Pasteurella multocida in PES was inhibited at 41 degrees C (febrile temperature for rabbits) as compared with 39 degrees C (afebrile temperature), suggesting the presence of an antibacterial agent active at febrile temperature. Further studies indicated that this antibacterial substance has a molecular weight less than 5000 Da. Heat treatment (70 degrees C, 1 hr) had no influence upon the activity of the inhibitory factor.

Topics: Animals; Ascitic Fluid; Crustacea; Fever; Glycogen; Hot Temperature; Leukocytes; Male; Molecular Weight; Pasteurella; Rabbits

Polymorphonuclear neutrophilic leukocytes of the dog, cat, and goat release leukocytic pyrogen under the same conditions as the heterophile polymorphonuclear leukocytes of the rabbit. The characteristics of the febrile response to an intravenous injection of homologous leukocytic pyrogen in all four species are very similar: a brisk monophasic fever reaching a peak between 30 and 50 min with smooth defervescence to the baseline by 3 hr. Shivering, which is not obvious in the rabbit, is noted in the dog, cat, and goat during the first 30 min. Quantitative differences in response reveal the cat to be the most sensitive of of these species to homologous leukocytic pyrogen, followed by the rabbit, dog, and goat. The response to heterologous pyrogen is in most cases markedly diminished compared to that after equal doses of homologous protein, suggesting the operation of species specificity, although canine and feline pyrogen behaved very similarly in all tests. Species specificity of leukocytic pyrogen is probably related to amino acid substitutions in different species of a common mammalian protein effector molecule.

Topics: Animals; Cats; Dogs; Fever; Glycogen; Goats; Leukocytes; Neutrophils; Peritonitis; Pyrogens; Rabbits; Species Specificity

Topics: Animals; Cell Nucleus; Dinitrophenols; DNA; Fever; Glycogen; Guinea Pigs; Histocytochemistry; Lipids; Liver; Methods; Milk; Mitochondria, Liver; Proteins; Rats; RNA

Topics: Adrenocorticotropic Hormone; Animals; Cerebral Cortex; Chlorpromazine; Fever; Glucocorticoids; Glycogen; Hypothermia; Rats

Topics: Adrenal Cortex Hormones; Adrenocorticotropic Hormone; Animals; Body Temperature; Cerebral Cortex; Chlorpromazine; Fever; Glycogen; Hypothermia; Hypothermia, Induced; Rats; Triamcinolone Acetonide