Models for nutritional research on the fetus: problems and pitfalls

Jones, C. T.; Michael, Enid; Lafeber, Harrie N.; Band, Geoffrey C.

doi:10.1079/pns19840040

Cited by 6 publications

(3 citation statements)

References 38 publications

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“…The significant decrease in maternal blood glucose was not reflected to the same extent in the fetus, suggesting two hypotheses: I ) an increased placental transport capacity to maintain adequate glucose transfer from maternal to fetal circulation; and/or 2) a rapid adaptation of fetal metabolism (increased liver glycogenolysis and gluconeogenesis) to compensate for a decrease in placental transfer of glucose. The present data do not permit determination of which mechanism is operative, but a premature appearance of fetal liver gluconeogenesis has been shown to occur during maternal fasting in the rabbit (22,23). The fall in fetal plasma insulin observed during maternal fasting could be explained by the fact that the fetal pancreas is sensitive to small changes of fetal glucose concentration as demonstrated in vitro (24) and in vivo (25) in the rat and in the sheep (26,27).…”

Section: Discussionmentioning

confidence: 75%

“…The fall in fetal plasma insulin observed during maternal fasting could be explained by the fact that the fetal pancreas is sensitive to small changes of fetal glucose concentration as demonstrated in vitro (24) and in vivo (25) in the rat and in the sheep (26,27). The decrease in fetal plasma insulin during fasting could be subsequently responsible for the premature induction of fetal liver phosphoenolpyruvate carboxykinase, the rate limiting enzyme of gluconeogenesis (22,23), and thereby preserve fetal glucose homeostasis.…”

Section: Discussionmentioning

confidence: 99%

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Glucose Utilization by the Placenta and Fetal Tissues in Fed and Fasted Pregnant Rabbits

et al. 1988

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ABSTRACT. Glucose utilization by the placenta and in- MATERIALS AND METHODSdividual fetal tissues was studied in vivo in conscious pregnant rabbits at 29 days of gestation. In the fed state, Animals. Female rabbits from the "Fauve de Bourgogne" strain the rate of glucose utilization was similar in the placenta were obtained from a breeder and were housed in and the gravid uterus, suggesting that the rate of fetal individual stainless steel cages. Mating was performed in the glucose utilization was approximately 40 nmol/min/g. A laboratory and the day of mating was taken as day zero of 96-h maternal fast induced a significant decrease in glucose pregnancy. On day 25 of gestation pregnant rabbits were sepautilization by the myoendometrium and in the glucose rated into two groups. The first group was fed a solid commercial utilization index by fetal liver and brown adipose tissue. rabbit diet ad libitum ( [480][481][482][483] 1988) pregnancy under ketamine hydrochloride (35 mg/kg intramuscularly) and xylazine hydrochloride (6 mg/kg intramuscularly) Abbreviations anesthesia. Under sterile conditions maternal vessels were cath-FFA, free fatty acids eterized. Polyvinyl catheters were inserted into one jugular vein 2DG, 2-deo~yl-[l-~H]glucose to allow radioactive tracer infusions and into one femoral artery GU, glucose uptake and one branch of the uterine vein for blood sampling under KB, ketone body conscious, unrestrained conditions (4). In addition, an intracardiac catheter was advanced to the left ventricle through the right carotid artery to allow blood flow measurements (4). All catheters were tied in place and tunneled subcutaneously to exit into a plastic cap sutured into place in the interscapular region. CathMetabolic requirements of the gravid uterus have been quan-eters were filled with an heparinized solution (800 IU/ml saline) tified in vivo in the cow (1) and the sheep (2) and more recently and were flushed every 3 days to keep them patent. Detailed in the guinea pig (3) and the rabbit (4). The growth and oxidative description of the surgical procedures has been reported previmetabolism of the mammalian fetus are largely dependent on ously (4). the rates of fetal glucose and amino acid utilization (5). Most of Measurements ofglucose utilization by theplacenta, the uterus, these studies have been carried out using chronic vascular cath-andfetal tissues. Experiments were carried out in vivo on day 29 eterization and measurements of overall substrate uptake by the of gestation in fed and 96-h fasted does. The radioactive 2-fetus and the placenta by means of the Fick principle method-deoxyglucose technique recently adapted to the rat fetus was ology. However, this technique does not permit determination used (9, 10). Glucose utilization index was determined in indiof substrate utilization by individual tissues of the fetus in small vidual tissues after an intravenous injection of 250 pCi 2DG in mammalian species.the conscious pregnant rabbits. Maternal arterial blood was In this respect, the rabbit is of ...

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Section: Discussionmentioning

confidence: 75%

Section: Discussionmentioning

confidence: 99%

Glucose Utilization by the Placenta and Fetal Tissues in Fed and Fasted Pregnant Rabbits

et al. 1988

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“…Growth-inhibiting substances are also released from the placenta when there is a reduction of uterine blood flow (193,195). Thus, there is a close relationship between placental perfusion and fetal size (110,194,314).…”

Section: Igf-ii In the Fetusmentioning

confidence: 99%