scholarly journals The metabolism of circulating non-esterified fatty acids by the whole animal, hind-limb muscle and uterus of pregnant ewes

1983 ◽  
Vol 49 (1) ◽  
pp. 129-143 ◽  
Author(s):  
D. W. Pethick ◽  
D. B. Lindsay ◽  
P. J. Barker ◽  
A. J. Northrop
Keyword(s):  
Fatty Acids ◽  
Hind Limb ◽  
Ketone Bodies ◽  
Gravid Uterus ◽  
Limb Muscle ◽  
Entry Rate ◽  
Esterified Fatty Acids ◽  
Arterial Concentration ◽  
Pregnant Sheep ◽  
Hind Limb Muscle

1. The over-all and regional metabolism of non-esterified fatty acids (NEFA) was studied using a combination of isotopic and arteriovenous-difference techniques.2. There was a common linear relationship, whether stearic, palmitic or oleic acids were used as tracer, between the arterial NEFA concentration and the rates of entry and oxidation.3. Assuming that the tracer used reflected the metabolism of all the NEFA, the total entry rate in fed and fasted pregnant ewes was (mean±SE) 0·44±0·02 and 0·55±0·07 mmol/h per kg body-weight respectively. Oxidation of NEFA contributed (mean±SE) 34±5 and 58±7% to the respiratory carbon dioxide in fed and fasted animals, this accounting for (mean±SE) 46±6 and 59±3% of the respective entry rates.4. Hind-limb muscle both utilized and produced NEFA. The mean gross fractional extraction (calculated from isotopic uptake) was (mean±SE) 9±1%. Gross utilization of any NEFA and appearance of 14CO2 across the muscle were linearly related to the arterial concentration of tracer fatty acid, irrespective of whether this was oleate or stearate. The amount of 14CO2 appearing was consistent with (mean±SE) 54±8% of the CO2 produced by the hind-limb being derived from NEFA oxidation.5. Infused NEFA were partly converted to ketone bodies. Uptake and oxidation in the hind-limb of ketones formed in the liver could account for approximately 20% of the 14CO2 apparently produced in muscle from NEFA. Correction for this reduces the proportion of CO2 derived from NEFA to 43%. There was some indication that ketones were also produced from NEFA in the hind-limb.6. NEFA were not a significant energy source for the gravid uterus.7. An over-all view of energy sources for the whole animal and for hind-limb muscle in normal and fasted pregnant sheep was presented.

scholarly journals Metabolism of ketone bodies in pregnant sheep

1982 ◽  
Vol 48 (3) ◽  
pp. 549-563 ◽  
Author(s):  
D. W. Pethick ◽  
D. B. Lindsay
Keyword(s):  
Skeletal Muscle ◽  
Hind Limb ◽  
Ketone Body ◽  
Ketone Bodies ◽  
Maximum Velocity ◽  
Compartment Model ◽  
Entry Rate ◽  
Arterial Concentration ◽  
Pregnant Sheep ◽  
Ketone Body Metabolism

1. A combination of isotope-dilution and arteriovenous-difference techniques was used to determine the significance of ketones to energy homoeostasis in fasted pregnant ewes.2. There was incomplete interconversion of D(−) 3-hydroxybutyrate (3HB) and acetoacetate (AcAc) and therefore neither entry rate nor oxidation of total ketone bodies could be estimated by assuming circulating ketone bodies represent a single metabolic compartment. Total ketone body metabolism was satisfactorily summarized using a three-compartment model. In fasted pregnant ewes the mean entry rate of total ketones was 1 mmol/h per kg body-weight and of the ketones entering the circulation 87% were promptly oxidized to carbon dioxide accounting for 30% of the total COa production.3. Ketone bodies are readily utilized by hind-limb skeletal muscle such that if completely oxidized, 18±4 and 48±3% of the oxygen utilized could be accounted for in fed and fasted pregnant ewes respectively. For both 3HB and AcAc there was a hyperbolic relationship between utilization and arterial concentration. The apparent Michaelis constant (Km) values were 0·55 and 1–42 mM respectively and the maximum velocity (Vmax) 2·9 and 5·6 mmol/h per kg muscle. The arterial concentration of AcAc is always below the Km value and this limits the utilization rate. The D(−) 3HB concentration, however, may surpass that required for maximum utilization and ketoacidosis may be a consequence of this.4. A two-compartment model was used to analyse ketone body metabolism by hind-limb skeletal muscle. The results suggested substantial intercon version and production of AcAc and 3HB.5. The pregnant uterus utilized 3HB which if completely oxidized accounted for 12±2 (fed) and 25±4 (fasted) % of its O2 consumption. At least 64% of the net 3HB utilized was oxidized. AcAc was not utilized in significant quantities.

scholarly journals Acetate Metabolism in the Mammary Gland of the Lactating Ewe

1985 ◽  
Vol 38 (1) ◽  
pp. 23 ◽  
Author(s):  
KR King ◽  
JM Gooden ◽  
EF Annison
Keyword(s):  
Fatty Acids ◽  
Mammary Gland ◽  
Whole Body ◽  
Acetate Metabolism ◽  
Acetate Production ◽  
Entry Rate ◽  
Esterified Fatty Acids ◽  
Arterial Concentration ◽  
Fatty Acid Carbon ◽  
Arteriovenous Difference

Acetate metabolism in the mammary gland of lactating ewes was studied by continuous infusion of radioisotopic [U-14C)sodium acetate and measurement of mammary gland arteriovenous difference and blood flow. Entry rate of acetate into the whole body averaged 75 � 7 /Lmol min -I kg -I liveweight and 22' I � 2 . 7 % of total C02 production was derived from acetate. Acetate was both utilized and produced by the mammary gland. Acetate uptake was related linearly (r2 = o� 94) to arterial concentration and gross utilization of acetate accounted for 16' 2 � 2 . 6 % of whole-body entry rate. Endogenous acetate production by the mammary gland increased linearly (r2 = O� 90) as milk yield rose, and accounted for 25 . 6 � 2 . 7 % of the gross mammary utilization of acetate. The proportion of mammary C02 derived from acetate (22' 5 � 3' 9%) was similar to that of the whole body. The uptake of acetate, 3-hydroxybutyrate, esterified fatty acids and plasma free fatty acids accounted for about 25, 13, 60 and 4% of milk fatty acid carbon respectively, after correction for the oxidation of acetate, but not of the other substrates. Metabolism of acetate in the mammary glands of lactating ewes appears quantitatively more important than that in cows, b~t similar to that in goats.

Ketone-Body Concentrations in Liver and Blood after Limb Ischaemia in the Rat

1971 ◽  
Vol 40 (6) ◽  
pp. 463-477 ◽  
Author(s):  
R. N. Barton
Keyword(s):  
Fatty Acids ◽  
Hind Limb ◽  
Ketone Body ◽  
Ketone Bodies ◽  
Regression Line ◽  
Early Response ◽  
Limb Ischaemia ◽  
Esterified Fatty Acids ◽  
Control Post ◽  
Body Concentration

1. The effect of a 4 h period of bilateral hind limb ischaemia on the concentrations of ketone bodies in blood and liver of post-absorptive and starved rats has been investigated. 2. The concentration of total ketone bodies in the blood did not change after injury in post-absorptive rats, but fell after injury in starved rats; the blood β-hydroxybutyrate/acetoacetate ratio fell after injury in both post-absorptive and starved rats. 3. Apart from a transient increase in fed rats, the hepatic β-hydroxybutyrate/acetoacetate ratio did not change after injury in post-absorptive or starved rats until the terminal stages, indicating adequate hepatic oxygenation during the early response to injury. 4. In control post-absorptive and starved rats the concentration of liver total ketone bodies was correlated with that of plasma non-esterified fatty acids; in post-absorptive rats the liver ketone body concentration rose after injury and was higher than would be predicted from the regression line for these controls, suggesting increased ketogenesis compatible with inhibition of complete oxidation of non-esterified fatty acids after injury. In contrast, in starved rats the liver total ketone-body concentration did not change after injury.

The effect of triamcinolone on glucose metabolism in ketotic sheep

1986 ◽  
Vol 106 (2) ◽  
pp. 337-340 ◽  
Author(s):  
E. J. H. Ford ◽  
Joan Evans
Keyword(s):  
Fatty Acids ◽  
Intramuscular Injection ◽  
Low Dose ◽  
Clinical Signs ◽  
Irreversible Loss ◽  
Entry Rate ◽  
Esterified Fatty Acids ◽  
Single Intramuscular Injection ◽  
Pregnant Sheep ◽  
Pregnancy Toxaemia

SUMMARYThe withdrawal of food from Clun Forest ewes pregnant with twins produced signs of pregnancy toxaemia accompanied by a significant decrease in the concentration of glucose, a significant increase in the concentration of ketones, non-esterified fatty acids (NEFA) and 3-hydroxybutyrate in plasma and a significant decrease in total entry rate and irreversible loss of glucose. A single intramuscular injection of 0·05 or 0·2 mg/kg of triamcinolone acetonide had no significant effect on the concentration of glucose, ketones or 3-hydroxybutyrate in plasma or on the total entry, irreversible loss or recycling of glucose in ketotic or in normal pregnant sheep. The low dose had a significant effect on the concentration of NEFA in plasma. Recovery from the clinical signs was slow after either dose of steroid but appeared to be hastened by the onset of parturition which was more rapid after the higher dose.

scholarly journals Non-esterified Long-chain Fatty Acid Metabolism in Fed Sheep at Rest and During Exercise

1987 ◽  
Vol 40 (2) ◽  
pp. 221 ◽  
Author(s):  
DW Pethick ◽  
N Harman ◽  
JK Chong
Keyword(s):  
Skeletal Muscle ◽  
Ketone Bodies ◽  
Long Chain Fatty Acids ◽  
Entry Rate ◽  
Long Chain Fatty Acid ◽  
Pregnant Sheep ◽  
Arteriovenous Difference ◽  
Long Chain ◽  
Sustained Increase

The role of circulating, non-esterified, long-chain fatty acids (NEFA) as a source of energy for the whole animal and skeletal muscle was investigated in fed non-pregnant sheep at rest and during exercise. Infusion of tracer quantities of [1-14C]oleic or [l-14C]stearic acid was combined with the use of arteriovenous difference studies on fed sheep at rest or during a 2 h period of exercise on a belt treadmill moving at 4� 5 km h -I. At rest all parameters of NEFA metabolism indicated a minimal role for oxidation. Thus the concentration in plasma (0'07 � 0�01 mmol I-I), entry rate (0'08 � 0�02 mmol h- I kg-I body wt), contribution to whole animal oxidation (1'2 � 0'3%) and utilization of NEFA by skeletal muscle (0'046 � 0�008 mmol h- I kg-I muscle) were all low. Exercise prompted a shift to lipolysis and accordingly the above parameters increased markedly some 13-24-fold. The circulating concentration of ketone bodies showed only a small increase during exercise and consequently the role of ketone bodies as an energy source during exercise was minimal. Glucose utilization by skeletal muscle was considerable in animals at rest and it represented the most significant potential fuel of skeletal muscle. Exercise resulted in a sustained increase of 3-4-fold in the utilization of glucose by skeletal muscle. Thus the traditional view that NEF A and not glucose is a predominant fuel of skeletal muscle of fed sheep should be appraised.

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