Plasma glucose turnover during cold stress in humans

1995 ◽  
Vol 78 (4) ◽  
pp. 1296-1302 ◽  
Author(s):  
A. L. Vallerand ◽  
J. Zamecnik ◽  
I. Jacobs
Keyword(s):  
Cold Stress ◽  
Cold Exposure ◽  
Plasma Glucose ◽  
Glucose Oxidation ◽  
Carbohydrate Oxidation ◽  
Whole Body ◽  
Gas Chromatography Mass Spectrometry ◽  
Glucose Turnover ◽  
Lactate Oxidation ◽  
The Difference

To clarify the source of increased carbohydrate oxidation during cold stress, six males rested for 3 h at 29 and 10 degrees C dressed only in shorts. After priming the blood glucose and bicarbonate pools, [U-13C6]glucose was infused for 3 h in each condition to determine the plasma glucose rate of appearance (Ra) or turnover under relative steady-state conditions. Plasma enrichment (mol %excess) was determined by selective ion-monitoring gas chromatography-mass spectrometry. Cold exposure decreased rectal temperature and mean skin temperature and increased heat debt, metabolic rate, and whole body lipid and carbohydrate oxidation (CHOox) compared with the same subjects at thermal neutrality (P < 0.05). Cold exposure significantly increased Ra from 13.18 +/- 0.70 to 16.22 +/- 0.43 mumol.kg-1.min-1 (P < 0.05). Plasma glucose clearance was elevated commensurately by the cold (from 2.68 +/- 0.16 to 3.55 +/- 0.14 ml.kg-1.min-1; P < 0.05). If we assume that Ra is completely oxidized (thus equivalent to maximum rates of plasma glucose oxidation) [J. A. Romijn, E. F. Coyle, L. S. Sidossis, A. Gastaldelli, J. F. Horowitz, E. Endert, and R. R. Wolfe. Am. J. Physiol. 265 (Endocrinol. Metab. 28): E380-E391, 1993], the minimum rates of glycogen and lactate oxidation in the cold would be the difference between CHOox and glucose oxidation (approximately 14.0 +/- 3.0 mumol.kg-1.min-1). Therefore, under the present laboratory conditions, 54% of CHOox would be fueled by plasma glucose oxidation, whereas the remaining 46% would be derived from the combination of glycogen and lactate oxidation.(ABSTRACT TRUNCATED AT 250 WORDS)

Glucose carbon recycling and oxidation in human newborns

1986 ◽  
Vol 251 (1) ◽  
pp. E71-E77 ◽  
Author(s):  
S. C. Denne ◽  
S. C. Kalhan
Keyword(s):  
Plasma Glucose ◽  
Glucose Oxidation ◽  
Cerebral Metabolism ◽  
Glucose Production ◽  
Carbohydrate Oxidation ◽  
Glucose Turnover ◽  
Total Carbohydrate ◽  
True Rate ◽  
Glucose Carbon ◽  
Carbon Recycling

Total carbohydrate oxidation, plasma glucose oxidation, and glucose carbon recycling were measured in 11 fasting newborns using a constant infusion of D-[U-13C]glucose combined with respiratory calorimetry. The "true" rate of glucose appearance (Ra) was quantified from the enrichment of the nonrecycling tracer species (m + 6), while the "apparent" rate of glucose appearance was quantified from the enrichment of glucose C - 1. The plasma glucose concentration remained constant at approximately 50 mg/dl (2.8 mM) throughout the study. The true rate of glucose production was 5.02 +/- 0.41 mg X kg-1 X min-1, (means +/- SD). Glucose was oxidized at a rate of 2.67 +/- 0.34 mg X kg-1 X min-1 and represented 53% of the glucose turnover. Recycling of glucose carbon represented 36% of the glucose production rate, or 1.87 +/- 0.74 mg X kg-1 X min-1. The oxidation of plasma glucose provided 15.8 +/- 2.0 kcal X kg-1 X day-1, whereas total carbohydrate oxidation (measured by respiratory calorimetry) provided 19.9 +/- 6.6 kcal X kg X day. The data indicate that 1) recycling of glucose carbon accounts for about one-third of glucose production, demonstrating active gluconeogenesis in the fasting newborn; 2) the oxidation of plasma glucose represents only 80% of total carbohydrate oxidation, the remaining 20% possibly representing the local oxidation of tissue glycogen stores; and 3) as the measured rate of glucose oxidation will be insufficient to supply the entire calculated cerebral metabolic requirements, these data suggest that fuels in addition to glucose may be important for cerebral metabolism in the fasting human newborn.

scholarly journals Leg and arm lactate and substrate kinetics during exercise

2003 ◽  
Vol 284 (1) ◽  
pp. E193-E205 ◽  
Author(s):  
G. van Hall ◽  
M. Jensen-Urstad ◽  
H. Rosdahl ◽  
H.-C. Holmberg ◽  
B. Saltin ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Muscle Mass ◽  
Lactate Concentration ◽  
Whole Body ◽  
Glucose Turnover ◽  
Lactate Oxidation ◽  
Arterial Lactate ◽  
Lactate Uptake ◽  
High Lactate

To study the role of muscle mass and muscle activity on lactate and energy kinetics during exercise, whole body and limb lactate, glucose, and fatty acid fluxes were determined in six elite cross-country skiers during roller-skiing for 40 min with the diagonal stride (Continuous Arm + Leg) followed by 10 min of double poling and diagonal stride at 72–76% maximal O2 uptake. A high lactate appearance rate (Ra, 184 ± 17 μmol · kg−1 · min−1) but a low arterial lactate concentration (∼2.5 mmol/l) were observed during Continuous Arm + Leg despite a substantial net lactate release by the arm of ∼2.1 mmol/min, which was balanced by a similar net lactate uptake by the leg. Whole body and limb lactate oxidation during Continuous Arm + Leg was ∼45% at rest and ∼95% of disappearance rate and limb lactate uptake, respectively. Limb lactate kinetics changed multiple times when exercise mode was changed. Whole body glucose and glycerol turnover was unchanged during the different skiing modes; however, limb net glucose uptake changed severalfold. In conclusion, the arterial lactate concentration can be maintained at a relatively low level despite high lactate Ra during exercise with a large muscle mass because of the large capacity of active skeletal muscle to take up lactate, which is tightly correlated with lactate delivery. The limb lactate uptake during exercise is oxidized at rates far above resting oxygen consumption, implying that lactate uptake and subsequent oxidation are also dependent on an elevated metabolic rate. The relative contribution of whole body and limb lactate oxidation is between 20 and 30% of total carbohydrate oxidation at rest and during exercise under the various conditions. Skeletal muscle can change its limb net glucose uptake severalfold within minutes, causing a redistribution of the available glucose because whole body glucose turnover was unchanged.

Effects of estrogen on whole animal and tissue glucose use in female and male rainbow trout

1992 ◽  
Vol 263 (6) ◽  
pp. R1241-R1247 ◽  
Author(s):  
B. S. Washburn ◽  
M. L. Bruss ◽  
E. H. Avery ◽  
R. A. Freedland
Keyword(s):  
Adipose Tissue ◽  
Rainbow Trout ◽  
Plasma Glucose ◽  
Ovarian Tissue ◽  
Glucose Consumption ◽  
Whole Body ◽  
Glucose Turnover ◽  
Sham Operation ◽  
Female Fish ◽  
Male Fish

Reports of changes in carbohydrate metabolism during vitellogenesis in fish prompted an investigation of the effects of estrogen on glucose utilization in rainbow trout. Estrogen pellets were implanted in both female and male fish, and a third group of male fish was given a sham operation. After cannulation of the dorsal aorta, D-[1-3H]glucose and 2-deoxy-D-[U-14C]glucose were injected into the fish to observe whole animal and tissue glucose use. We found that estrogen does not affect glucose turnover rate or transit time but causes a decrease in plasma glucose concentration and size of the glucose mixing pool. Adipose tissue in female fish utilized glucose at a higher rate than sham fish. Ovarian tissue used more glucose per kilogram of body weight than the testes of the male fish. Regardless of treatment, brain had the highest rate of glucose consumption per gram of tissue, followed by gonads and red blood cells. Muscle and adipose tissue utilized only small amounts (< 1 nmol.g tissue-1.min-1) of glucose. We conclude that an increase in the rate of whole body glucose use is not responsible for the fall in plasma glucose caused by estrogen and seen during vitellogenesis.

THE POOL SIZE, TURNOVER RATE, AND OXIDATION RATE OF BODY GLUCOSE IN ANESTHETIZED WARM- AND COLD-ACCLIMATED RATS EXPOSED TO A WARM ENVIRONMENT

1959 ◽  
Vol 37 (1) ◽  
pp. 285-295 ◽  
Author(s):  
Florent Depocas
Keyword(s):  
Body Weight ◽  
Plasma Glucose ◽  
Turnover Time ◽  
The Body ◽  
Pool Size ◽  
Glucose Turnover ◽  
Oxidation Rates ◽  
Warm Environment ◽  
Essentially Normal ◽  
The Difference

The size and space of the body glucose pool along with its turnover and oxidation rates have been measured in anesthetized 30° and 6 °C acclimated rats by a method involving continuous intravenous injection of small amounts of D-glucose uniformly labelled with C14 and attainment of relatively constant specific activities of plasma glucose and respiratory CO2. Values of glucose pool space in warm-acclimated rats (essentially normal animals) were in accord with those found in the dog by a similar method. Results obtained on warm-acclimated rats indicated that previous published values of turnover and oxidation rates of glucose for normal rats were high by a factor of approximately 2 to 4. There was, however, close agreement between the values of turnover time of body glucose pool measured by the continuous infusion procedure and those obtained by others with the single intravenous or intraperitoneal injection procedure. In cold-acclimated rats, average absolute values of glucose pool size were significantly smaller than in warm-acclimated rats but the difference was lost when results were related to body weight. Small, non-significant differences in values of glucose pool size per 100 g body weight and in plasma glucose concentration combined to give a significantly larger glucose space in cold-than in warm-acclimated rats. Glucose turnover and oxidation rates, the ratio between these two quantities, and the proportion of respiratory CO2 derived from glucose oxidation were not significantly different in the two groups of rats, thus indicating that cold acclimation is not associated with major alterations in glucose metabolism at least when studied on fully fed anesthetized animals at 30 °C.

Effect of cold exposure on plasma glucose and acetate turnover rates in sheep

2014 ◽  
Vol 54 (10) ◽  
pp. 1728 ◽  
Author(s):  
M. Al-Mamun ◽  
Y. Sako ◽  
H. Sano
Keyword(s):  
Plasma Concentration ◽  
Cold Exposure ◽  
Plasma Glucose ◽  
Turnover Rate ◽  
Isotopic Dilution ◽  
Glucose Turnover ◽  
Acetate Metabolism ◽  
Turnover Rates ◽  
Water Access ◽  
Esterified Fatty Acids

Isotopic dilution methodology of [U-13C]glucose and [1-13C]Na-acetate were performed simultaneously as primed continuous infusions to determine plasma glucose and acetate metabolism in sheep during thermoneutral (TN) and cold exposure (CE, 2−4°C). The experiment was performed using crossbred (Corriedale × Suffolk) sheep (n = 5; 3 male and 2 female; ~2 years old, 38 ± 2.5 kg of initial bodyweight). The animals were offered mixed hay of orchardgrass and reed canarygrass (40 : 60) 62 g/kg0.75/day with ad libitum water access. Concentration of plasma glucose was determined enzymatically using the glucose oxidase method. Plasma concentration of non-esterified fatty acids (NEFA) and glucose were higher (P = 0.01 and P = 0.05 respectively) during CE than TN. Plasma concentration and the turnover rate of acetate were numerically higher (P = 0.09 and P = 0.25 respectively) during CE than during TN. Plasma glucose turnover rate was higher (P = 0.02) during CE than TN. The present findings suggested that plasma acetate turnover rate tended to be elevated during CE, with further more extensive studies required to clarify the significance.

Influence of fasting on carbohydrate and fat metabolism during rest and exercise in men

1988 ◽  
Vol 64 (5) ◽  
pp. 1923-1929 ◽  
Author(s):  
J. J. Knapik ◽  
C. N. Meredith ◽  
B. H. Jones ◽  
L. Suek ◽  
V. R. Young ◽  
...  
Keyword(s):  
Plasma Glucose ◽  
Muscle Glycogen ◽  
Ketone Bodies ◽  
Carbohydrate Oxidation ◽  
Metabolic Effects ◽  
Whole Body ◽  
Time To Exhaustion ◽  
Carbohydrate Utilization ◽  
Insulin Levels ◽  
Glucose Flux

Metabolic effects of an overnight fast (postabsorptive state, PA) or a 3.5-day fast (fasted state, F) were compared in eight healthy young men at rest and during exercise to exhaustion at 45% maximum O2 uptake. Glucose rate of appearance (Ra) and disappearance (Rd) were calculated from plasma glucose enrichment during a primed, continuous infusion of [6,6–2H]glucose. Serum substrates and insulin levels were measured and glycogen content of the vastus lateralis was determined in biopsies taken before and after exercise. At rest, whole-body glucose flux (determined by the deuterated tracer) and carbohydrate oxidation (determined from respiratory exchange ratio) were lower in F than PA, but muscle glycogen levels were similar. During exercise, glucose flux, whole-body carbohydrate oxidation, and the rate of muscle glycogen utilization were significantly lower during the fast. In the PA state, glucose Ra and Rd increased together throughout exercise. However, in the F state Ra exceeded Rd during the 1st h of exercise, causing an increase in plasma glucose to levels similar to those of the PA state. The increase in glucose flux was markedly less throughout F exercise. Lower carbohydrate utilization in the F state was accompanied by higher circulating fatty acids and ketone bodies, lower plasma insulin levels, and the maintenance of physical performance reflected by similar time to exhaustion.

Manipulation of dietary carbohydrate and muscle glycogen affects glucose uptake during exercise when fat oxidation is impaired by β-adrenergic blockade

2004 ◽  
Vol 287 (6) ◽  
pp. E1195-E1201 ◽  
Author(s):  
Theodore W. Zderic ◽  
Simon Schenk ◽  
Christopher J. Davidson ◽  
Lauri O. Byerley ◽  
Edward F. Coyle
Keyword(s):  
Glucose Uptake ◽  
Plasma Glucose ◽  
Muscle Glycogen ◽  
Fat Oxidation ◽  
Whole Body ◽  
Moderate Intensity ◽  
Glucose Turnover ◽  
Adrenergic Blockade ◽  
High Fat ◽  
Carbohydrate Diet

We have recently reported that, during moderate intensity exercise, low muscle glycogen concentration and utilization caused by a high-fat diet is associated with a marked increase in fat oxidation with no effect on plasma glucose uptake (Rd glucose). It is our hypothesis that this increase in fat oxidation compensates for low muscle glycogen, thus preventing an increase in Rd glucose. Therefore, the purpose of this study was to determine whether low muscle glycogen availability increases Rd glucose under conditions of impaired fat oxidation. Six cyclists exercised at 50% peak O2 consumption (V̇o2 peak) for 1 h after 2 days on either a high-fat (HF, 60% fat, 24% carbohydrate) or control (CON, 22% fat, 65% carbohydrate) diet to manipulate muscle glycogen to low and normal levels, respectively. Two hours before the start of exercise, subjects ingested 80 mg of propanolol (βB), a nonselective β-adrenergic receptor blocker, to impair fat oxidation during exercise. HF significantly decreased calculated muscle glycogen oxidation ( P < 0.05), and this decrease was partly compensated for by an increase in fat oxidation ( P < 0.05), accompanied by an increase in whole body lipolysis ( P < 0.05), despite the presence of βB. Although HF increased fat oxidation, plasma glucose appearance rate, Rd glucose, and glucose clearance rate were also significantly increased by 13, 15, and 26%, respectively (all P < 0.05). In conclusion, when lipolysis and fat oxidation are impaired, in this case by βB, fat oxidation cannot completely compensate for a reduction in muscle glycogen utilization, and consequently plasma glucose turnover increases. These findings suggest that there is a hierarchy of substrate compensation for reduced muscle glycogen availability after a high-fat, low-carbohydrate diet, with fat being the primary and plasma glucose the secondary compensatory substrate. This apparent hierarchy likely serves to protect against hypoglycemia when endogenous glucose availability is low.

scholarly journals Hypoxic cutaneous vasodilation is sustained during brief cold stress and is not affected by changes in CO2

2010 ◽  
Vol 108 (4) ◽  
pp. 788-792 ◽  
Author(s):  
Grant H. Simmons ◽  
Sarah M. Fieger ◽  
Christopher T. Minson ◽  
John R. Halliwill
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Cold Stress ◽  
Skin Blood Flow ◽  
Cold Exposure ◽  
Whole Body ◽  
Cutaneous Vasodilation ◽  
Hypercapnic Hypoxia ◽  
Hypoxic Vasodilation ◽  
The Impact

Hypoxia decreases core body temperature in animals and humans during cold exposure. In addition, hypoxia increases skin blood flow in thermoneutral conditions, but the impact of hypoxic vasodilation on vasoconstriction during cold exposure is unknown. In this study, skin blood flow was assessed using laser-Doppler flowmetry, and cutaneous vascular conductance (CVC) was calculated as red blood cell flux/mean arterial pressure and normalized to baseline ( n = 7). Subjects were exposed to four different conditions in the steady state (normoxia and poikilocapnic, isocapnic, and hypercapnic hypoxia) and were cooled for 10 min using a water-perfused suit in each condition. CVC increased during all three hypoxic exposures (all P < 0.05 vs. baseline), and the magnitude of these steady-state responses was not affected by changes in end-tidal CO2 levels. During poikilocapnic and hypercapnic hypoxia, cold exposure reduced CVC to the same levels observed during normoxic cooling ( P > 0.05 vs. normoxia), whereas CVC remained elevated throughout cold exposure during isocapnic hypoxia ( P < 0.05 vs. normoxia). The magnitude of vasoconstriction during cold stress was similar in all conditions ( P > 0.05). Thus the magnitude of cutaneous vasodilation during steady-state hypoxia is not affected by CO2 responses. In addition, the magnitude of reflex vasoconstriction is not altered by hypoxia, such that the upward shift in skin blood flow (hypoxic vasodilation) is maintained during whole body cooling.

High-fat hypocaloric diet modifies carbohydrate utilization of obese rats during weight loss

2001 ◽  
Vol 280 (5) ◽  
pp. E797-E803 ◽  
Author(s):  
Ming C. Cha ◽  
Julia A. Johnson ◽  
Chang-Yun Hsu ◽  
Carol N. Boozer
Keyword(s):  
Weight Loss ◽  
Glucose Transport ◽  
Food Restriction ◽  
Glucose Oxidation ◽  
Fat Content ◽  
Carbohydrate Oxidation ◽  
Hypocaloric Diet ◽  
Whole Body ◽  
Adipose Depot ◽  
Obese Rats

The effects of fat content in the hypocaloric diet on whole body glucose oxidation and adipocyte glucose transport were investigated in two animal-feeding experiments. Diet-induced obese rats were food restricted to 75% of their previous energy intakes with either a high (45% by calorie) or a low (12% by calorie) corn oil diet for 9 wk ( experiment 1) or 10 days ( experiment 2). The losses of body weight ( P< 0.05) and adipose depot weight ( P < 0.05) were less in the 45% compared with the 12% fat group. During the dynamic phase of weight loss ( day 10 of food restriction), plasma glucose and insulin concentrations were higher ( P < 0.05) in the 45% than those in the 12% fat group. Whole body carbohydrate oxidation rate in response to an oral load of glucose was increased ( P < 0.001) by food restriction in both dietary groups; however, carbohydrate oxidation rates were lower ( P < 0.01) in the 45% than in the 12% fat-fed rats during the weight loss period. Adipocyte glucose transport was greater ( P < 0.02) in the 45% than in the 12% fat group in an intra-abdominal adipose depot but not in subcutaneous fat. These data suggest that dietary fat content modifies whole body glucose oxidation and intra-abdominal adipocyte glucose uptake during weight loss.

Effect of cold exposure on fuel utilization in humans: plasma glucose, muscle glycogen, and lipids

2002 ◽  
Vol 93 (1) ◽  
pp. 77-84 ◽  
Author(s):  
François Haman ◽  
François Péronnet ◽  
Glen P. Kenny ◽  
Denis Massicotte ◽  
Carole Lavoie ◽  
...  
Keyword(s):  
Heat Production ◽  
Cold Exposure ◽  
Plasma Glucose ◽  
Muscle Glycogen ◽  
Glucose Oxidation ◽  
Future Research ◽  
Oxidation Rates ◽  
Low Intensity ◽  
Glucose Ingestion ◽  
Shivering Thermogenesis

The relative roles of circulatory glucose, muscle glycogen, and lipids in shivering thermogenesis are unclear. Using a combination of indirect calorimetry and stable isotope methodology ([U-13C]glucose ingestion), we have quantified the oxidation rates of these substrates in men acutely exposed to cold for 2 h (liquid conditioned suit perfused with 10°C water). Cold exposure stimulated heat production by 2.6-fold and increased the oxidation of plasma glucose from 39.4 ± 2.4 to 93.9 ± 5.5 mg/min (+138%), of muscle glycogen from 126.6 ± 7.8 to 264.2 ± 36.9 mg glucosyl units/min (+109%), and of lipids from 46.9 ± 3.2 to 176.5 ± 17.3 mg/min (+376%). Despite the observed increase in plasma glucose oxidation, this fuel only supplied 10% of the energy for heat generation. The major source of carbohydrate was muscle glycogen (75% of all glucose oxidized), and lipids produced as much heat as all other fuels combined. During prolonged, low-intensity shivering, we conclude that total heat production is unequally shared among lipids (50%), muscle glycogen (30%), plasma glucose (10%), and proteins (10%). Therefore, future research should focus on lipids and muscle glycogen that provide most of the energy for heat production.

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