Fructose Disposal and Oxidation Rates in the Ovine Fetus

Meznarich, Huei K.; Hay, William W.; Sparks, John W.; Meschia, Giacomo; Battaglia, Frederick C.

doi:10.1113/expphysiol.1987.sp003102

Cited by 56 publications

(36 citation statements)

References 10 publications

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“…The present study indicates that lactate is unlikely to make a major contribution to the metabolic balance of the equine uteroplacental tissue. Similarly, there is little evidence for significant fructose oxidation by the uteroplacental tissues in either the pregnant sheep or horse (Silver, 1981;Meznarich et al 1987;McGowan et al 1995). Amino acids also appear to be less readily available as metabolic substrates in the uteroplacental tissues of the horse than sheep during late gestation (Carter et al 1991;Silver et al 1994;Chung et al 1998).…”

Section: Discussionmentioning

confidence: 99%

Equine Uteroplacental Metabolism at Mid‐ and Late Gestation

Fowden¹,

Forhead²,

White³

et al. 2000

Experimental Physiology

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Uptakes of oxygen, glucose and lactate by the gravid uterus, fetus and uteroplacental tissues were measured in chronically catheterized pregnant ponies and their fetuses at mid‐ and late gestation (term 335 days). Rates of O2 uptake by the gravid uterus, fetus and uteroplacental tissues were significant at both gestational ages and were 2‐ to 3‐fold higher in late gestation than the mid‐gestation values of 3338 ± 794, 1352 ± 258 and 2035 ± 602 μmol min‐1, respectively (n = 4). Similarly, there were significant uptakes of glucose by the gravid uterus, fetus and uteroplacental tissues at both mid‐ and late gestation. However, unlike O2 uptake, glucose uptake by the uterus and uteroplacental tissues did not increase between mid‐ and late gestation. No significant uptakes or outputs of lactate were observed by the uterus or uteroplacental tissues at either gestational age, although there was a significant umbilical uptake of lactate in late but not mid‐gestation. There was no change in the distribution of uterine O2 uptake between the fetus and uteroplacental tissues with increasing gestational age. The uteroplacental tissues accounted for about 50% of the uterine O2 uptake at both gestational ages. In contrast, the proportion of the uterine glucose uptake used by the uteroplacental tissues decreased from 73.2 ± 2.1% (n = 5) at mid‐gestation to 61.1 ± 1.9% (n = 4, P < 0.02) in late gestation. The gestational changes in uteroplacental carbohydrate metabolism in the mare differ from those seen in the ewe and may have important consequences for the duration and outcome of pregnancy in the mare.

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Section: Discussionmentioning

confidence: 99%

Equine Uteroplacental Metabolism at Mid‐ and Late Gestation

Fowden¹,

Forhead²,

White³

et al. 2000

Experimental Physiology

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“…These species bear similar placental types (synepithelioor epitheliochorial placentas) and maintain relatively low maternal glucose concentrations, which may require placental fructogenic capacity to supply the concepti with adequate amounts of reducing sugars during pregnancy (Goodwin 1956, Hugget & Nixon 1961). An increase in glucose supply and consumption by the placenta linearly redirects the use of this substrate to non-oxidative pathways, such as fructose synthesis (Meznarich et al 1987, Hay 1995. Placental fructose production may be a byproduct of the foetal need on occasion to supply glucose to the placenta, preventing glucose loss to the mother, as fructose does not cross the foetomaternal barrier, and limiting foetal glucose uptake when placental needs are high (Gu et al 1987).…”

Section: Discussionmentioning

confidence: 99%

Evidence of increased substrate availability to in vitro-derived bovine foetuses and association with accelerated conceptus growth

Bertolini

Moyer²,

Mason³

et al. 2004

Reproduction

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Changes in placental development have been associated with foetal abnormalities after in vitro embryo manipulations. This study was designed to investigate bovine conceptus development and substrate levels in plasma and fluids in in vivo-and in vitro-produced (IVP) concepti and neonates. In vivo-produced and IVP embryos were derived by established embryo production procedures. Pregnant animals from both groups were slaughtered on days 90 or 180 of gestation, or allowed to go to term. Conceptus and neonatal physical traits were recorded; foetal, maternal and neonatal blood, and foetal fluids were collected for the determination of blood and fluid chemistry, and glucose, fructose and lactate concentrations. Placental transcripts for specific glucose transporters were determined by quantitative RT-PCR. No significant differences in uterine and conceptus traits were observed between groups on day 90. On day 180, larger uterine, placental and foetal weights, and an increase in placental gross surface area (SA) in IVP pregnancies were associated with increased glucose and fructose accumulation in foetal plasma and associated fluids, with no differences in the expression of components of the glucose transporter system. Therefore, the enlarged placental SA in IVP pregnancies suggests an increase in substrate uptake and transport capacity. Newborn IVP calves displayed higher birth weights and plasma fructose concentrations soon after birth, findings which appeared to be associated with clinical and metabolic distress. Our results indicated larger concepti and increased placental fructogenic capacity in mid-to late IVP pregnancies, features which appeared to be associated with an enhanced substrate supply, potentially glucose, to the conceptus.

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“…In bovine and porcine models, fetal fructose levels were reported to be 3-to 4-fold higher than maternal fructose levels under normal fed conditions. 28,29 In 1 human study, a 40% fructose solution was administered to mothers just prior to delivery and cord blood fructose levels were analyzed. In this model, which may reflect the diabetic conditions, cord fructose levels increased 3-fold in response to elevated maternal fructose levels.…”

Section: Discussionmentioning

confidence: 99%

Asymmetric Syncytial Expression of GLUT9 Splice Variants in Human Term Placenta and Alterations in Diabetic Pregnancies

2011

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Glucose transport from the maternal to fetal side of the placenta is critical for fetal growth and development due to the absence of fetal gluconeogenesis. Human GLUT9, existing as 2 isoforms, is a novel member of the transporter family. This study investigated the localization and relative expression levels of these isoforms in the human term placenta from both control and diabetic patients. Placenta samples were collected from normal pregnancies and those complicated by maternal diabetes (White classifications A1, A2, and B). Antibodies specific for the different isoforms were used to detect expression. Both forms of the protein are expressed in syncytiotrophoblast cells. Subcellular fractionation revealed an asymmetrical expression pattern with GLUT9a on basal membranes, whereas GLUT9b localizes to microvillus membranes. Expression of both isoforms is significantly increased in placental tissue from diabetic pregnancies. Altered expression of GLUT9 in the placenta may play a role in the fetal pathophysiology associated with diabetes-complicated pregnancies.

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Fructose Disposal and Oxidation Rates in the Ovine Fetus

Cited by 56 publications

References 10 publications

Equine Uteroplacental Metabolism at Mid‐ and Late Gestation

Equine Uteroplacental Metabolism at Mid‐ and Late Gestation

Evidence of increased substrate availability to in vitro-derived bovine foetuses and association with accelerated conceptus growth

Asymmetric Syncytial Expression of GLUT9 Splice Variants in Human Term Placenta and Alterations in Diabetic Pregnancies

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