Regulation of plasma free fatty acid turnover

1961 ◽  
Vol 201 (1) ◽  
pp. 9-15 ◽  
Author(s):  
D. T. Armstrong ◽  
R. Steele ◽  
N. Altszuler ◽  
A. Dunn ◽  
J. S. Bishop ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Free Fatty Acid ◽  
Plasma Free Fatty Acid ◽  
Mass Action ◽  
Turnover Rates ◽  
Pharmacological Treatments ◽  
Simple Mass ◽  
Plasma Ffa ◽  
Specific Activities ◽  
The Relationship

Plasma free fatty acid (FFA) turnover rates have been estimated in dogs by a technique involving measurement of FFA specific activities during constant intravenous infusion of trace amounts of C14-labeled palmitic acid. In order to determine the relationship between FFA concentration and turnover, variations in plasma FFA levels ranging from 0.081 to 3.31 µEq/ml were induced by a variety of physiological and pharmacological treatments. Calculated FFA turnover rates ranged from 2.1 to 58.8 µEq/kg/min, with a highly significant linear regression of FFA turnover on FFA level. It is concluded that under a variety of conditions changes in FFA concentration are brought about by changes in FFA production rate and that changes in FFA uptake are simple mass-action effects of changes in FFA concentration. Respiratory C14O2 data are presented indicating that about one-fourth of the total expired CO2 is derived from FFA in the postabsorptive state. This accounts for the immediate fate of about one-fourth of the total FFA leaving the plasma.

An assessment of the energy requirements of the pregnant ewe using plasma free fatty acid concentrations

1971 ◽  
Vol 77 (1) ◽  
pp. 141-145 ◽  
Author(s):  
J. J. Robinson ◽  
C. Fraser ◽  
C. Bennett
Keyword(s):  
Body Weight ◽  
Fatty Acid ◽  
Birth Weight ◽  
Free Fatty Acid ◽  
Plasma Free Fatty Acid ◽  
Metabolizable Energy ◽  
Energy Requirements ◽  
Plasma Ffa ◽  
Pregnant Ewe ◽  
The Relationship

SummaryAn experiment was conducted in which 57 North Country Cheviot ewes, bearing variable foetal loads, were offered different amounts of feed intake during the latter half of gestation. Plasma free fatty acid (FFA) concentrations were estimated at 10-day intervals during the last 55 days of gestation. From the relationship between FFA concentration, energy intake, lamb birth weight and ewe body weight, estimates of the energy requirements of the pregnant ewe were predicted.The additional metabolizable energy (ME) intake above maternal maintenance required to prevent elevation of plasma FFA concentrations above a predetermined basal level 5 days pre-partum was calculated as 335 kcal/kg lamb birth weight.The results obtained from the use of plasma FFA concentrations in assessing the energy requirements of the pregnant ewe are discussed in relation to those obtained by other methods.

The Effects of Cold and Prostaglandin E1 on Lipid Mobilization in the Chicken

1971 ◽  
Vol 49 (5) ◽  
pp. 394-398 ◽  
Author(s):  
W. D. Wagner ◽  
R. A. Peterson ◽  
R. J. Cenedella
Keyword(s):  
Fatty Acid ◽  
Free Fatty Acid ◽  
Cold Exposure ◽  
Prostaglandin E1 ◽  
Plasma Free Fatty Acid ◽  
Prostaglandin E ◽  
Elevated Plasma ◽  
Lower Plasma ◽  
Lipid Mobilization ◽  
Plasma Ffa

Plasma free fatty acid (FFA) levels and the effects of prostaglandin E1 (PGE1) were studied in cold-acclimated and cold-exposed chickens and compared to controls. Chickens cold-acclimated at 4–7 or 8–11 °C for 4 weeks had significantly elevated plasma FFA when compared to the controls at 19–21 °C. Although PGE1 had no effect on the basal level of FFA of controls, a significantly lower plasma FFA was seen after injection of either 10 or 30 μg PGE1/kg in cold-acclimated chickens. Chickens cold-exposed to 2–3 °C for 4 h demonstrated significant elevations of plasma FFA when compared to controls. Only 30 μg PGE1/kg significantly depressed the plasma FFA in the cold-exposed birds. No inhibition of basal FFA release was seen in control animals. From these experiments, it is concluded that chickens mobilize FFA extensively under cold-exposure and that this stimulated lipolysis is inhibited by PGE1.

Dose-dependent effect of insulin on plasma free fatty acid turnover and oxidation in humans

1990 ◽  
Vol 259 (5) ◽  
pp. E736-E750 ◽  
Author(s):  
R. C. Bonadonna ◽  
L. C. Groop ◽  
K. Zych ◽  
M. Shank ◽  
R. A. DeFronzo
Keyword(s):  
Fatty Acid ◽  
Free Fatty Acid ◽  
Lipid Oxidation ◽  
Plasma Insulin ◽  
Plasma Free Fatty Acid ◽  
Whole Body ◽  
Glucose Disposal ◽  
Body Lipid ◽  
Plasma Ffa ◽  
Dose Dependent

Methodology for measuring plasma free fatty acid (FFA) turnover/oxidation with [1–14C]palmitate was tested in normal subjects. In study 1, two different approaches (720-min tracer infusion without prime vs. 150-min infusion with NaH14CO3 prime) to achieve steady-state conditions of 14CO2 yielded equivalent rates of plasma FFA turnover/oxidation. In study 2, during staircase NaH14CO3 infusion, calculated rates of 14CO2 appearance agreed closely with NaH14CO3 infusion rates. In study 3, 300-min euglycemic insulin clamp documented that full biological effect of insulin on plasma FFA turnover/oxidation was established within 60–120 min. In study 4, plasma insulin concentration was raised to 14 +/- 2, 23 +/- 2, 38 +/- 2, 72 +/- 5, and 215 +/- 10 microU/ml. A dose-dependent insulin suppression of plasma FFA turnover/oxidation was observed. Plasma FFA concentration correlated positively with plasma FFA turnover/oxidation in basal and insulinized states. Total lipid oxidation (indirect calorimetry) was significantly higher than plasma FFA oxidation in the basal state, suggesting that intracellular lipid stores contributed to whole body lipid oxidation. Hepatic glucose production and total glucose disposal showed the expected dose-dependent suppression and stimulation, respectively, by insulin. In conclusion, insulin regulation of plasma FFA turnover/oxidation is maximally manifest at low physiological plasma insulin concentrations, and in the basal state a significant contribution to whole body lipid oxidation originates from lipid pool(s) that are different from plasma FFA.

scholarly journals Plasma free fatty acid concentration is closely tied to whole body peak fat oxidation rate during repeated exercise

2019 ◽  
Vol 126 (6) ◽  
pp. 1563-1571 ◽  
Author(s):  
Jacob Frandsen ◽  
Stine Dahl Vest ◽  
Christian Ritz ◽  
Steen Larsen ◽  
Flemming Dela ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Free Fatty Acid ◽  
Body Fat ◽  
Oxidation Rate ◽  
Plasma Free Fatty Acid ◽  
Fat Oxidation ◽  
Whole Body ◽  
Exercise Tests ◽  
Repeated Exercise ◽  
Plasma Ffa

Plasma free fatty acids (FFA) are a major contributor to whole body fat oxidation during exercise. However, the extent to which manipulating plasma FFA concentrations will influence whole body peak fat oxidation rate (PFO) during exercise remains elusive. In this study we aimed to increase plasma FFA concentrations through a combination of fasting and repeated exercise bouts. We hypothesized that an increase in plasma FFA concentration would increase PFO in a dose-dependent manner. Ten healthy young (31 ± 6 yr) (mean ± SD) well-trained (maximal oxygen uptake 65.9 ± 6.1 ml·min−1·kg−1) men performed four graded exercise tests (GXTs) on 1 day. The GXTs were interspersed by 4 h of bed rest. This was conducted either in a fasted state or with the consumption of a standardized carbohydrate-rich meal 3.5 h before each GXT. Fasting and previous GXTs resulted in a gradual increase in PFO from 0.63 ± 0.18 g/min after an overnight fast (10 h) to 0.93 ± 0.17 g/min after ∼22 h of fasting and three previous GXTs. This increase in PFO coincided with an increase in plasma FFA concentrations ( r2 = 0.73, P < 0.0001). Ingestion of a carbohydrate-rich meal 3.5 h before each GXT resulted in unaltered PFO. This was also reflected in unchanged plasma FFA, glucose, and insulin concentrations. In this study we show that plasma FFA availability is closely tied to whole body PFO and that the length of fasting combined with previous exercise are robust stimuli toward increasing plasma FFA concentration, highlighting the importance for preexercise standardization when conducting GXTs measuring substrate oxidation. NEW & NOTEWORTHY We show that peak fat oxidation is increased in close relationship with plasma free fatty acid availability after combined fasting and repeated incremental exercise tests in healthy highly trained men. Therefore it may be argued that whole body fat oxidation rate measured in most cases after an overnight fast indeed does not represent whole body maximal fat oxidation rate but a whole body peak fat oxidation rate within the context of the preexercise standardization obtained in the study design.

Effect of endurance training on plasma free fatty acid turnover and oxidation during exercise

1993 ◽  
Vol 265 (5) ◽  
pp. E708-E714 ◽  
Author(s):  
W. H. Martin ◽  
G. P. Dalsky ◽  
B. F. Hurley ◽  
D. E. Matthews ◽  
D. M. Bier ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Free Fatty Acid ◽  
Exercise Training ◽  
Endurance Exercise ◽  
Prolonged Exercise ◽  
Plasma Free Fatty Acid ◽  
Cycle Ergometer ◽  
Endurance Exercise Training ◽  
Plasma Ffa ◽  
Total Fat

Plasma free fatty acid (FFA) levels tend to be lower and the plasma lipolytic hormone response to prolonged exercise of the same intensity is blunted after endurance exercise training. To determine whether training elicits a corresponding decrease in plasma FFA turnover and metabolism during prolonged exercise, we measured plasma [1-13C]palmitate kinetics and oxidation and respiratory gas exchange in 13 subjects during the latter portion of a 90- to 120-min bout of cycle ergometer work performed before and after 12 wk of alternate-day cycling and running. Training increased total fat oxidation during prolonged exercise by 41% (P < 0.005). However, for the final 30-60 min of the cycle ergometer protocol, the rate of 13CO2 production from [1-13C]palmitate oxidation was 27% lower (P < 0.05), the rate of palmitate turnover was 33% less (P < 0.05), and plasma FFA and glycerol concentrations were 32 and 20% lower (P < 0.05), respectively, than in the untrained state. Thus endurance exercise training results in decreased plasma FFA turnover and oxidation during a 90- to 120-min bout of submaximal exercise because of a slower rate of FFA release from adipose tissue.

scholarly journals Peak Fat Oxidation Rate Is Closely Associated With Plasma Free Fatty Acid Concentrations in Women; Similar to Men

2021 ◽  
Vol 12 ◽  
Author(s):  
Jacob Frandsen ◽  
Axel Illeris Poggi ◽  
Christian Ritz ◽  
Steen Larsen ◽  
Flemming Dela ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Free Fatty Acid ◽  
Plasma Free Fatty Acid ◽  
Fat Oxidation ◽  
Whole Body ◽  
Men And Women ◽  
Fed State ◽  
Repeated Exercise ◽  
Graded Exercise ◽  
Plasma Ffa

Introduction: In men, whole body peak fat oxidation (PFO) determined by a graded exercise test is closely tied to plasma free fatty acid (FFA) availability. Men and women exhibit divergent metabolic responses to fasting and exercise, and it remains unknown how the combined fasting and exercise affect substrate utilization in women. We aimed to investigate this, hypothesizing that increased plasma FFA concentrations in women caused by fasting and repeated exercise will increase PFO during exercise. Then, that PFO would be higher in women compared with men (data from a previous study).Methods: On two separate days, 11 young endurance-trained women were investigated, either after an overnight fast (Fast) or 3.5 h after a standardized meal (Fed). On each day, a validated graded exercise protocol (GXT), used to establish PFO by indirect calorimetry, was performed four times separated by 3.5 h of bed rest both in the fasted (Fast) or fed (Fed) state.Results: Peak fat oxidation increased in the fasted state from 11 ± 3 (after an overnight fast, Fast 1) to 16 ± 3 (mean ± SD) mg/min/kg lean body mass (LBM) (after ~22 h fast, Fast 4), and this was highly associated with plasma FFA concentrations, which increased from 404 ± 203 (Fast 1) to 865 ± 210 μmol/L (Fast 4). No increase in PFO was found during the fed condition with repeated exercise. Compared with trained men from a former identical study, we found no sex differences in relative PFO (mg/min/kg LBM) between men and women, in spite of significant differences in plasma FFA concentrations during exercise after fasting.Conclusion: Peak fat oxidation increased with fasting and repeated exercise in trained women, but the relative PFO was similar in young trained men and women, despite major differences in plasma lipid concentrations during graded exercise.

Mechanism of regulation of glucose production by lipolysis in humans

1992 ◽  
Vol 262 (3) ◽  
pp. E353-E358 ◽  
Author(s):  
F. Jahoor ◽  
S. Klein ◽  
R. Wolfe
Keyword(s):  
Fatty Acid ◽  
Free Fatty Acid ◽  
Nicotinic Acid ◽  
Plasma Insulin ◽  
Glucose Production ◽  
Plasma Free Fatty Acid ◽  
Insulin Levels ◽  
Plasma Insulin Levels ◽  
Normal Humans ◽  
The Relationship

The relationship between the rate of lipolysis and rate of glucose production (Ra) was investigated in 14- and 86-h fasted humans. [6,6-2H]glucose and [2H]5glycerol were infused to measure glucose and glycerol Ra in response to infusions of nicotinic acid in 14- and 86-h fasted subjects (protocol 1). The response of glucose Ra to nicotinic acid alone and nicotinic acid plus unlabeled glycerol was also measured in 86-h fasted subjects (protocol 2). After a 14-h fast, nicotinic acid caused a 30% decrease in plasma insulin levels and a marked (66%) decrease in plasma free fatty acid levels but did not have any significant effect on glucose Ra and concentration. After 86 h of fasting, nicotinic acid decreased glycerol Ra and hence lipolytic rate by approximately 60%. This caused a significant decrease (P less than 0.05) of 16-20% in glucose Ra and uptake. This decrease in glucose Ra was abolished when unlabeled glycerol was also infused with nicotinic acid to maintain glycerol Ra. These findings suggest that, in normal humans, a decrease in the rate of lipolysis regulates glucose Ra via its effect on the availability of glycerol for gluconeogenesis.

Effect of glucagon on thermogenesis in the pigeon.

1977 ◽  
Vol 232 (5) ◽  
pp. E451
Author(s):  
E Hohtola ◽  
R Hissa ◽  
S Saarela
Keyword(s):  
Oxygen Consumption ◽  
Fatty Acid ◽  
Blood Glucose ◽  
Free Fatty Acid ◽  
Plasma Free Fatty Acid ◽  
Energy Reserves ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Plasma Ffa ◽  
Adrenergic Blocking

The effects of glucagon injection on temperature regulation and some metabolic parameters were studied in the pigeon. Glucagon (100 microng/kg) always inhibited shivering and caused a fall in the oxygen consumption and body temperature of the unanesthetized pigeon at + 6 degrees C. At + 34 degrees C, the same dose of glucagon had no effect on these parameters. At 22 degrees C, glucagon produced an elevation in plasma free fatty acid (FFA) and blood glucose levels. The rise in FFA at 22 degrees C coincided with the suppression of shivering at 6 degrees C. The glucagon-mediated rise in plasma FFA, but not glucose level, was potentiated by cold ambient temperature. Adrenergic blocking agents given prior to glucagon did not abolish its effects. Phentolamine even prolonged the absence and accelerated the suppression of shivering. A dissociation in the mechanisms by which catecholamines and glucagon suppress shivering is suggested. Although mobilizing energy reserves, glucagon does not seem to be calorigenic in the pigeon at this dose. The interpretation of the changes in plasma FFA levels is discussed in relation to fuel consumption during shivering.

Effect of exercise on FFA metabolism of pancreatectomized dogs

1963 ◽  
Vol 205 (4) ◽  
pp. 645-650 ◽  
Author(s):  
B. Issekutz ◽  
H. I. Miller ◽  
K. Rodahl
Keyword(s):  
Fatty Acid ◽  
Free Fatty Acid ◽  
Specific Activity ◽  
Plasma Free Fatty Acid ◽  
Fat Oxidation ◽  
Striking Difference ◽  
Heavy Exercise ◽  
Plasma Ffa ◽  
Ffa Metabolism ◽  
Pancreatectomized Dogs

Normal and pancreatectomized dogs with indwelling arterial and venous catheters were exercised on the treadmill for 35 min. Palmitate-1-C14 was infused intravenously for 3 hr during the experiment, or administered orally 15 hr before the experiment. The plasma free fatty acid (FFA) level was decreased in normal dogs but increased in the pancreatectomized animals during exercise. This was due to corresponding changes in the rate of FFA release. The rate of uptake of plasma FFA followed the rate of release with some delay, so that at the end of exercise the uptake was tenfold higher in the pancreatectomized dogs than in the controls. In spite of this striking difference, the C14O2 output was increased during exercise four- to fivefold in both groups in the infusion experiments. When the radiopalmitate was administered orally, however, the specific activity of the exhaled C14O2 rapidly decreased in the exercising pancreatectomized dogs but remained rather constant in the controls. It is suggested that during heavy exercise the muscles of the normal dog oxidize their endogenous fat pools, whereas the pancreatectomized animal relies for fat oxidation on the plasma FFA, the concentration of which is considerably increased by norepinephrine in the absence of insulin.

Effect of growth hormone of free fatty acid metabolism

1964 ◽  
Vol 206 (1) ◽  
pp. 174-178 ◽  
Author(s):  
Bertram Winkler ◽  
Robert Steele ◽  
Norman Altszuler ◽  
Richard C. de Bodo
Keyword(s):  
Growth Hormone ◽  
Fatty Acid ◽  
Free Fatty Acid ◽  
Turnover Rate ◽  
Acid Metabolism ◽  
Plasma Free Fatty Acid ◽  
Transient Effect ◽  
Free Fatty Acid Metabolism ◽  
Plasma Ffa ◽  
Ffa Metabolism

Bovine growth hormone ( GH) was administered at 1 mg/kg day for various periods of time to normal dogs. The effects produced on plasma free fatty acid ( FFA) metabolism were studied in these animals, in the unanesthetized state, using palmitate-C14. At 3–9 hr following intravenous injection of growth hormone significant increase were observed in plasma FFA concentration, turnover rate, total amount of FFA oxidized to CO2, and per cent of total respiratory CO2 derived from FFA. FFA production was increased by GH; FFA uptake and oxidation increased in parallel with plasma FFA concentration and apparently were not affected directly by GH. Similar changes were observed after 2 days of GH. After 7 days of GH all these parameters returned to control values. The transient effect of GH on FFA metabolism is in contrast with its reported prolonged effects on fat metabolism; possible reasons for this discrepancy are discussed.

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