Glucose metabolism in the placenta

Walker, Deryck G.; Lea, Michael A.; Rossiter, Guillermo; Addison, M.E.B.

doi:10.1016/0003-9861(67)90530-9

Cited by 30 publications

(12 citation statements)

References 22 publications

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“…In creasing the glucose concentration in the assay mixture up to 100 nmol/1, we never observed a corresponding increase in the phosphorylating activity. This is in accordance with Walker et al [39] and largely rules out the presence of a specific glukokinase in the villous tissue. This enzyme is not present in placentas of other species as well [39].…”

Section: Discussionsupporting

confidence: 69%

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Glycolytic Enzymes in the Normal Human Term Placenta

Gustke¹,

Kowalewski²

1975

Enzyme

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The enzymes hexokinase (HK), phosphoglucomutase (PGM), pyruvate kinase (PK) and lactate dehydrogenase (LDH) were assayed in villous tissue homogenates and cell fractions of normal human term placentas. Although lowest in activity and probably rate limiting in glycolysis, hexokinase is theoretically adequate to phosphorylate the total amount of glucose metabolized. PGM and PK activity were in the same range exceeding HK by 10-15 times, suggesting a largely increased breakdown of glycogenderived glucose in situations of need. Substantially higher LDH activities may reflect the placental ability to utilize lactate from both mother and fetus. Of all enzymes only hexokinase was found to be associated with the particulate matter in considerable amounts.

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Section: Discussionsupporting

confidence: 69%

“…Direct measurements of glycolytic enzyme activities in the placenta have rarely been performed hitherto. As shown by Walker et al [39] phosphory lation of glucose is the rate-limiting step in placental glycolysis. In our experiments, too, hexokinase was far less active than the other enzymes.…”

Section: Discussionmentioning

confidence: 99%

Glycolytic Enzymes in the Normal Human Term Placenta

Gustke¹,

Kowalewski²

1975

Enzyme

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“…Placental glucose-6-phosphatase is thought to be absent at this time (21). These results indicate that either there is some glucose-6-phosphatase activity or the glycogen is continually being utilized by the placenta for its own metabolism.…”

Section: Discussionmentioning

confidence: 56%

The Effect of Maternal Hypothyroidism on Maternal and Fetal Tissue Glucose-1-<sup>14</sup>C Incorporation in Rats

Porterfield¹,

Hendrich²

1975

Horm Res

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These experiments were conducted to help elucidate the mechanism for the impaired fetal development occurring during maternal hypothyroidism. The disposition of glucose was measured using glucose-1-¹⁴C. Maternal hypothyroidism depressed glucose utilization in the maternal-fetal system. Maternal net glycogen synthesis from the labeled glucose was impaired. However, while the fetal glycogen storage system may be capable of at least relatively normal glycogen synthesis, abnormally low levels of glycogen were measured. If, as the data suggest, enzymatic deficiencies do not exist, the low liver glycogen might be a result of the inability of the maternal-placental system to provide adequate substrate to the fetus.

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“…Bernard (9) and Villee (10) postulated that placental glycogen is a storage depot for fetal use and that it serves to regulate fetal blood glucose levels, but it has been shown that under conditions of fetal stress, glucose is not liberated from the placenta and glycogen levels are not reduced (11,12). Also, enzyme studies have shown that the placenta throughout gestation lacks the enzyme glucose-6-phosphatase (EC 3.1.3.9), which is necessary for the final release of glucose from glycogen (13,14). The placental glycogen is therefore considered by Robb and Hutten (12) to be more likely a store for local use, perhaps playing a role as an emergency energy reserve for vasomotor function.…”

Section: Discussionmentioning

confidence: 99%

Glycogen Deposition in Fetal Mouse Tissues and the Effect of Dexamethasone

Tye

Burton²

1980

Neonatology

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Glycogen in fetal mouse tissues was isolated and determined using the anthrone method on gestational days 14–19. Fetal liver showed rapid glycogen deposition after gestational day 17, reaching a value of 46.7 mg/g wet weight on day 19. Heart and placenta showed sizable glycogen stores earlier, with peak values of 21.7 and 12.8 mg/g, respectively, on day 16 which declined thereafter. Lung maintained approximately 10 mg/g days 16–19; gut and brain contained approximately 2 and 4 mg/g, respectively, days 14–19. After injection of dexamethasone into mothers on gestational day 15.5, 16 h prior to assay, the glycogen content of liver increased approximately tenfold, while placental glycogen declined. This indicates that corticosteroids merely accelerate the pattern observed in the normal course of gestation.

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Glucose metabolism in the placenta

Cited by 30 publications

References 22 publications

Glycolytic Enzymes in the Normal Human Term Placenta

Glycolytic Enzymes in the Normal Human Term Placenta

The Effect of Maternal Hypothyroidism on Maternal and Fetal Tissue Glucose-1-<sup>14</sup>C Incorporation in Rats

Glycogen Deposition in Fetal Mouse Tissues and the Effect of Dexamethasone

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