EFFECT OF COLD EXPOSURE ON RESPIRATORY C14O2 PRODUCTION DURING INFUSION OF ALBUMIN-BOUND PALMITATE-1-C14 IN WHITE RATS

1961 ◽  
Vol 39 (2) ◽  
pp. 219-224 ◽  
Author(s):  
Roberto Masironi ◽  
Florent Depocas
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Cold Exposure ◽  
Carbohydrate Utilization ◽  
White Rats ◽  
Constant Rate ◽  
Oxidation Of Glucose ◽  
Fasted Rats

Albumin palmitate-1-C14 complex was infused at a constant rate through a carotid cannula (inserted 5–7 days earlier) into otherwise intact non-fasted rats in environments at 30° or 6 °C, after acclimation to 30° or 6 °C. At 6 °C, both warm- and cold-acclimated rats similarly exhaled as CI4O2 a larger proportion of the injected C14 and gave lower terminal amounts of C14 in the extracted free fatty acids (F.F.A.) of plasma than at 30 °C. These results indicate that plasma F.F.A. serve as substrate for cold-thermogenesis. Also, increased turnover and oxidation of F.F.A. are not always inversely related to carbohydrate utilization but may be increased under conditions which result in concomitantly higher rates of turnover and oxidation of glucose.

PLASMA GLUCOSE, LACTATE AND FREE FATTY ACID RESPONSES TO ADRENALINE IN CHRONICALLY WARM- AND COLD-EXPOSED SHEEP

1981 ◽  
Vol 61 (4) ◽  
pp. 919-924 ◽  
Author(s):  
A. D. GRAHAM ◽  
G. D. PHILLIPS
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Free Fatty Acid ◽  
Free Fatty Acids ◽  
Cold Exposure ◽  
Plasma Glucose ◽  
Plasma Free Fatty Acid ◽  
Temperature Treatment ◽  
Glucose Response ◽  
Adrenaline Infusion

The effects of chronic cold exposure, fasting, or both on the plasma metabolite responses to jugular infusions of adrenaline were studied in eight five-mo-old wether lambs. Following maintenance at 20–22 °C or −4 to 10 °C for 2–3 wk the sheep received adrenaline infusions (0.15 μg∙kg−1∙min−1) for 75 min prior to and following a 72-h fast. Plasma samples collected at intervals of 10–15 min before and during adrenaline infusion were analyzed for glucose, lactate and total free fatty acids. Chronic cold exposure had no effect on the pre-infusion plasma glucose, lactate or free fatty acid concentrations. Fasting decreased plasma glucose and lactate and increased plasma free fatty acid concentrations. The plasma glucose response to adrenaline was greater (P < 0.01) in cold- than warm-exposed sheep and fasting depressed this response to a greater extent in the cold-exposed sheep. The plasma lactate response to adrenaline was not influenced by temperature treatment or fasting. Both groups of fasted sheep showed a large increase in plasma free fatty acids during adrenaline infusion but when fed the response was minimal.

Body glucose as fuel in white rats exposed to cold: results with fasted rats

1962 ◽  
Vol 202 (5) ◽  
pp. 1015-1018 ◽  
Author(s):  
Florent Depocas
Keyword(s):  
Energy Metabolism ◽  
Plasma Volume ◽  
Heat Production ◽  
Glucose Concentration ◽  
Glucose Oxidation ◽  
Volume Of Distribution ◽  
White Rats ◽  
Elevated Glucose ◽  
Oxidation Of Glucose ◽  
Fasted Rats

Concentration of glycogen in liver and muscle of warm- and cold-acclimated rats was measured during fasting at 30 or 6 C. The biokinetics of glucose were then studied by priming and continuous infusion with C14-labeled glucose in 24-hr-fasted rats exposed to 30, 18, and 6 C. In warm-acclimated rats at 18 and 6 C there were higher rates of turnover and oxidation of glucose than at 30 C and the ratio of rates of oxidation to turnover increased, but glucose concentration in plasma, volume of distribution of glucose, and proportion of respiratory CO2 derived from glucose remained constant in the three environments. Cold-acclimated rats at 6 C had higher values of glucose concentration in plasma, of volume of distribution of glucose, and a slightly higher rate of turnover of glucose than warm-acclimated rats at 6 C. Gluconeogenesis thus can satisfy the elevated glucose requirement in the cold, and the fasted rat increases its heat production by an increase in glucose oxidation proportionate to the increase in energy metabolism as does the nonfasted animal.

Elevated muscle citrate does not reduce carbohydrate utilization during tetanic stimulation

1994 ◽  
Vol 72 (2) ◽  
pp. 117-125 ◽  
Author(s):  
David J. Dyck ◽  
Lawrence L. Spriet
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Hind Limb ◽  
Tetanic Stimulation ◽  
Phosphate Content ◽  
Carbohydrate Utilization ◽  
Rest Perfusion ◽  
Glycogen Utilization ◽  
White Gastrocnemius ◽  
Intense Stimulation

The purposes of this study were to determine whether enhanced free fatty acid delivery would result in increased muscle citrate levels and to establish whether the effects of this putative phosphofructokinase inhibitor would be manifested during intense stimulation demanding glycogen as a fuel. Hind-limb muscles were perfused with either no or high (0.93 ± 0.03 mM) free fatty acids for 10 min at rest, and during 5 min of tetanic stimulation. Muscles sampled at the end of the rest perfusion or stimulation were soleus (slow oxidative), red gastrocnemius (fast oxidative glycolytic), and white gastrocnemius (fast glycolytic). Muscle citrate content was unaffected during rest perfusion with no free fatty acids, whereas high free fatty acids significantly elevated citrate above control in soleus, red gastrocnemius, and white gastrocnemius (by 0.39 ± 0.13, 0.53 ± 0.10, and 0.29 ± 0.07 μmol∙g−1 dry muscle, respectively). Following 1 min of stimulation, citrate content in soleus and red gastrocnemius was not different from control in the absence of free fatty acids but accumulated significantly with high free fatty acids (0.26 ± 0.05 and 0.28 ± 0.04 μmol∙g−1 dry muscle, respectively). Following 5 min of stimulation, soleus and red gastrocnemius citrate content decreased with no free fatty acids but increased significantly with high free fatty acids (0.42 ± 0.10 μmol∙g−1 dry muscle) in soleus and remained unchanged in red gastrocnemius. The presence of high free fatty acids had no effect on glycogen utilization or lactate accumulation in stimulated soleus and red gastrocnemius, or stimulated white gastrocnemius citrate, glycogen, or lactate contents. In addition, no effect of elevated free fatty acids on resting or stimulated muscle glucose-6-phosphate content, glucose uptake, or lactate efflux was observed. In conclusion, the elevation of muscle citrate due to the presence of free fatty acids in the perfusate did not reduce muscle glycogenolysis when the demand for energy was great.Key words: citrate glycolysis, phosphofructokinase, glycogen.

Variation of plasma ketones and free fatty acids during acute cold exposure in man

1965 ◽  
Vol 20 (1) ◽  
pp. 56-60 ◽  
Author(s):  
Peter G. Hanson ◽  
Robert E. Johnson
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Cold Exposure ◽  
Ketone Bodies ◽  
Control Period ◽  
Exposure Period ◽  
Nonesterified Fatty Acids ◽  
Acute Cold Exposure ◽  
Plasma Ffa ◽  
And Control

We have studied the magnitude of ketosis induced during acute cold exposure. Plasma and urinary ketone bodies and plasma free fatty acids (FFA) were followed in four healthy young men at rest during a 90-min period of seminude exposure to 0 C in still air. This period was followed by 4 hr of recovery at 25 C. Each subject served as his own control throughout an experimental sequence in which one cold-exposure and corresponding control period (25 C) were experienced each week for 3 successive weeks. The subjects were in a fasting state but with water ad libitum beginning 12 hr prior to the experiment. Light weight clothing was worn during recovery and control periods. The combined group data show a significant increase in plasma FFA during cold exposure as compared with similar control periods. Although true hyperketonemia or hyperketonuria did not develop, the levels of plasma ketones are elevated in the cold-exposure period of the first week. During the second and third week there is no difference between the cold and control plasma ketone concentration. The data suggest that FFA is mobilized as a metabolic substrate during cold exposure and that efficient peripheral utilization of the elevated plasma FFA concentration minimizes hyperketogenesis. ketone bodies; metabolism; nonesterified fatty acids Submitted on April 27, 1964

Turnover rate and oxidation of different free fatty acids in man during exercise

1964 ◽  
Vol 19 (4) ◽  
pp. 613-618 ◽  
Author(s):  
Richard J. Havel ◽  
Lars A. Carlson ◽  
Lars-Göran Ekelund ◽  
Alf Holmgren
Keyword(s):  
Fatty Acids ◽  
Plasma Concentration ◽  
Free Fatty Acids ◽  
Relative Abundance ◽  
Healthy Subjects ◽  
Turnover Rate ◽  
Accurate Assessment ◽  
Plasma Triglycerides ◽  
Constant Rate ◽  
Fractional Turnover

Palmitate-9, 10-H3 has been infused intravenously at a constant rate together with various C14-labeled fatty acids in healthy subjects at rest and during exercise. No significant differences in the rates of fractional turnover were found between H3-labeled palmitate and C14-labeled palmitate or oleate. Retention of a considerably larger fraction of C14-labeled linoleate in the blood plasma precluded accurate assessment of its fractional turnover rate. The rates of oxidation of palmitate-I-C14, palmitate-U-C14, oleate-I-C14, and linoleate-I-C14 during exercise were similar. The relative abundance of palmitate, oleate, and linoleate in the free fatty acids of plasma changed little during exercise. It is concluded that palmitate-I-C14 is a valid tracer for measuring the turnover rate and oxidation of at least three-fourths of circulating free fatty acids under the conditions of study. Recycling of radioactivity in triglyceride fatty acids of plasma was similar for H3-labeled palmitate and C14-labeled palmitate and oleate, both at rest and during exercise. The plasma concentration of glycerol increased promptly with exercise. Changes in its concentration closely followed those in the turnover rate of free fatty acids, but were of greater magnitude. plasma glycerol during exercise; plasma triglycerides, formation from different FFA; respiratory quotient during exercise Submitted on October 4, 1963

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