A-V Differences of Free Fatty Acids and Glycerol in the Ovine Umbilical Circulation

James, Elizabeth; Meschia, Giacomo; Battaglia, Frederick C.

doi:10.3181/00379727-138-35999

Cited by 55 publications

(25 citation statements)

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“…The possibility of increased umbilical uptake of other substrates for catabolism and growth have also been investigated. It would seem in the fetal sheep that acetoacetate, betahydroxybutyrate (17,20), long chain free fatty acids (15,20) and fructose (20) are not taken up by the fetus in significant quantities when the ewe is fed or during severe maternal starvation. Therefore, it would seem that in the fetal sheep the metabolic adaptations of the human adult of increasing availability of ketones and free fatty acids for oxidative metabolism are not present.…”

Section: Speculationmentioning

confidence: 99%

Fetal and Maternal Hormonal Response to Starvation in the Ewe

et al. 1980

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SummaryFive ewes 90-130 days of gestation with chronically indwelling fetal catheters were studied. Blood samples were drawn each morning simultaneously from the maternal femoral artery, fetal femoral artery, and fetal umbilical vein. Total starvation was begun after blood samples had been drawn on the 3rd morning, but water was given ad libitum. The mean maternal arterial plasma glucose concentration before starvation (73.4 2 31.0 (SEM) mg/100 ml plasma HzO) fell to 54.8 f 5.2 mg/100 ml (P < 0.01) after 24 hr of fasting and to 37.5 + 1.6 mg/100 ml (P < 0.001) by 72 hr of fasting. The maternal arterial fructose concentration was low in both the fed (2.9 f 0.4 mg/100 ml) and fasted states (1.8 + 0.5 mg/100 ml, day 3). The maternal arterial insulin concentration fell early in fasting from a mean of 27.9 + 3.9 uU/ml on 2 days before starvation to 12.4 + 1.8 uU/ml after 24 hr of fasting (P < 0.005) and remained low for the duration of the 7-day fasting period. The mean maternal arterial glucagon concentration in the fed state was 112 + 20 pg/ml and did not change significantly throughout the 7 days of maternal fasting.Fetal arterial plasma glucose was much lower than maternal levels (mean 18.4 + 1.1 mg/100 ml plasma Hz0 in the fed state), decreased to 12.1 + 1.4 mg/100 ml after 24 hr of fasting ( P < 0.05) and did not change significantly after the 1st day of fasting.The whole blood fructose concentration in the fetal artery was high in the fed state (71.7 + 11.5 mg/100 ml, mean 2 days before fasting) and fell quickly during starvation (54.2 2 3.4 mg/100 ml after 48 hr). The fructose concentration did not change further for the duration of the fasting period. The fetal arterial insulin concentration was lower than the maternal (19.4 + 1.0 uU/ml in the fed state and did not fall dramatically after fasting as the mother did. After 24 hr of fasting, the fetal insulin was 15.0 + 1.5 uU/ml ( P < 0.005) and remained low throughout the fast. The umbilical venous-arterial differences of insulin were statistically different from 0 in both fed (mean -1.4 f 0.3 u U / d , P < 0.005) and fasted state (mean -1.4 + 0.5 uU/d, P < 0.02), with the fetal artery greater than the umbilical vein in 25 of 28 measurements. The fetal arterial concentration of glucagon was lower than in the ewe (32 f 7 pg/ml) and also did not change significantly during starvation.There was a good correlation of the plasma glucose and insulin concentrations for: both the fetus and the ewe. Analvsis of ~ooled fetal and maternal regression lines for insulin-glucos~relatidnships reveals no difference in the slow (maternal 0.48. fetal 0.48). but a statistically significant differeice'in the y intercept (mateinal -7.70, fetal 8.65, P < 0.005), with the fetal curve shifted to the left.The excellent correlation between plasma glucose and insulin concentration throughout the fed and fasted periods suggests that the decrease in fetal plasma glucose and the decreased utilization of exogenous glucose by the fetus is mediated by fetal insulin level. Although the respons...

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Section: Speculationmentioning

confidence: 99%

Fetal and Maternal Hormonal Response to Starvation in the Ewe

et al. 1980

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“…Measurements of the difference in concentration of free fatty acids (FFA) in umbilical arterial and venous blood have indicated a net flux of fatty acids to the foetus in rabbits (Elphick et al 1975) and man (Persson & Tunnell, 1971;Sheath, Grimwade, Waldron, Bickley, Taft & Wood 1972;Elphick, Hull & Sanders, 1976). Measurements on umbilical blood samples from sheep did not show a net flux in either direction (James, Meschia & Battaglia, 1971). In rabbits and man the umbilical venous-arterial difference varied directly with the maternal FFA blood concentrations (Elphick et al 1975;Elphick et al 1976;Aabata, Wolf & Lausmann, 1968).…”

Section: Introductionmentioning

confidence: 99%

The transfer of free fatty acids across the rabbit placenta.

Elphick¹,

Hull²

1977

The Journal of Physiology

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SUMMARY1. The passage of fatty acids across the placenta was studied in 28 day pregnant rabbits (i) by comparing the fatty acid distribution in plasma free fatty acids (FFA) of umbilical cord artery and vein with that in maternal plasma and (ii) by infusing the doe at a constant rate with labelled palmitic, linoleic or arachidonic acids. During the infusion maternal and foetal plasma FFA specific activities were measured.2. The mean levels of all the fatty acids studied (from twelve to twenty carbon atoms) were similar in both the umbilical vein plasma and maternal arterial plasma FFA, except for arachidonic acid, which was higher in foetal blood. The relative distribution of the fatty acids in umbilical arterial plasma was similar to that in the vein, but at lower concentrations. The mean cord venous-arterial difference for each fatty acid correlated positively with the mean maternal arterial levels, with the exception of arachidonic acid.3. During the constant infusion experiments the specific activities of the fatty acids in the maternal and foetal circulating FFA pools rose rapidly during the first 4 min then rose only slowly. Palmitic and linoleic acids were cleared from the maternal circulation in a similar manner and crossed the placenta at similar rates.4. The average foetal specific activity in plasma FFA reached 15 % of the maternal level for both palmitate and linoleate. The figure for arachidonic acid was half that for palmitic acid infused at the same time.5. It is concluded that (i) all the major fatty acids present in foetal adipose tissue cross the placenta, (ii) the net transport of each fatty acid depends in part on maternal concentrations, (iii) the rate of metabolism of palmitic and linoleic acids is the same and both cross the placenta at the same rate. Proportionately less foetal arachidonic acid is derived from maternal FFA, and (iv) the results suggest a second placental source of arachidonic acid and possibly also of other fatty acids.

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“…Fructose [12], medium and long chain free fatty acids, and glycerol [7], acetoacetate, and /3-hydroxybutyrate [3] were found to make little or no contribution to the balance of oxidative substrate. On the other hand, the fetal lamb was shown to have a high urea production rate which could account for as much as 25% of the fetal oxygen consumption through the catabolism of amino acids [5].…”

Section: Introductionmentioning

confidence: 99%

Glucose/Oxygen Quotients across the Hindlimb of Fetal Lambs

et al. 1973

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ExtractGlucose/oxygen quotients were determined across the hindlimbs of seven fetuses, for a total of five studies in fetuses of fed ewes and five studies in fetuses of fasted ewes. The glucose/oxygen quotient was found to be a function of the fetal arterial glucose concentration in mM, [a], described by the equation: glucose/oxygen quotient = -0.047 + 1.46 [a]. The dependence of glucose uptake by the fetal hindlimb upon arterial glucose concentration is the first demonstration of the effect of substrate availability on the metabolism of a fetal organ. SpeculationThe demonstration of glucose/oxygen quotients of 1.0 or greater for fetal tissues at a time in gestation when the umbilical glucose/oxygen quotient is 0.4-0.5 suggests two possible explanations: (/) there may be substrate specificity for oxidative metabolism for each fetal organ, and (2) non-glucose substrates such as amino acids taken up by the umbilical circulation may be utilized by the fetal liver for gluconeogenesis.

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A-V Differences of Free Fatty Acids and Glycerol in the Ovine Umbilical Circulation

Cited by 55 publications

References 0 publications

Fetal and Maternal Hormonal Response to Starvation in the Ewe

Fetal and Maternal Hormonal Response to Starvation in the Ewe

The transfer of free fatty acids across the rabbit placenta.

Glucose/Oxygen Quotients across the Hindlimb of Fetal Lambs

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