The Transplacental Potential Difference in Guinea-Pigs

S̆tulc, J.; Rietveld, W.J.; Soeteman, D.W.; Versprille, A.

doi:10.1159/000240503

Cited by 14 publications

(5 citation statements)

References 6 publications

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“…Relatively high flows are obtained which are within the range found by Shepherd and Whelan (6) with umbilical arterial pressure comparable to those found in the fetus. The potential difference across the placenta (19 mV) is comparable to that found between fetus and mother (21 mV) (7). No oedema was present even after prolonged perfusion, and the perfusion was uniform throughout the tissue despite the use of only one umbilical artery.…”

Section: Discussionsupporting

confidence: 63%

Technique for <i>in situ</i> Perfusion of the Guinea Pig Placenta

Fenton¹

1977

Neonatology

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Section: Discussionsupporting

confidence: 63%

Technique for <i>in situ</i> Perfusion of the Guinea Pig Placenta

Fenton¹

1977

Neonatology

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“…The stability of the perfusate reservoir's volume (allowing for sample loss) indicated little formation of oedema or loss of fluid to the mother. Mean terminal potential differences of 19 mV with perfusate negative to the mother were similar to those between guinea-pig foetus and mother ( §tulc, Rietveld, Soeteman & Versprille, 1972). Two control perfusions were performed in which samples were taken from the maternal circulation and perfusate at 10 min intervals.…”

mentioning

confidence: 69%

Permeability of the Foetal Guinea-Pig Placenta to Arginine-Vasopressin

Forsling¹,

Fenton²

1977

Journal of Endocrinology

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“…In this species the foetal side is approximately 20 mV negative with respect to the maternal side (Mellor, 1969; 8tulc, Rietveld, Soeteman & Versprille, 1972). The p.d.…”

Section: Introductionmentioning

confidence: 77%

“…On such grounds active transport of Na from the foetal to the maternal 692 PLACENTAL TRANSPORT OF Na side of the placenta has been postulated and examined experimentally in the guinea-pig (8tulc & 8vihovec, 1973). In this species the foetal side is approximately 20 mV negative with respect to the maternal side (Mellor, 1969; 8tulc, Rietveld, Soeteman & Versprille, 1972). The p.d.…”

Section: Introductionmentioning

confidence: 77%

Placental transport of sodium in the guinea‐pig.

S̆tulc¹,

Švihovec²

1977

The Journal of Physiology

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SUMMARY1. The mechanism of placental transport of Na was studied in guineapigs in placentae with intact umbilical blood circulation or in the preparation of the placenta perfused in situ.2. A constant level of 22Na was maintained in maternal plasma for 60 min, and from the quantity of 22Na recovered from the foetus at the end of this period the influx of Na from mother to foetus was calculated. Ligation of the omphalomesenteric vessels (supplying the everted yolk sac with blood) had no effect on the influx, the corresponding values of influx in the control and treated foetuses being 0-235 + 0-020 and 0-247 + 0*029 ,u-mole/min . g foetal weight (n = 6, the limits are S.E. of mean). The specific activity of Na in amniotic fluid was below that of the maternal or foetal plasma Na by two orders of magnitude. These observations indicate that the extraplacental transport of Na into the foetus is negligibly low.3. The electrical potential difference (p.d.) and unidirectional fluxes of Na across the placenta perfused in situ were measured by means of 22Na and 24Na administered to the opposite sides of the placental barrier. The fluxes varied with the weight of the foetuses whose placentae were perfused.The flux from the maternal to the foetal side was 0-270 + 0-017 ,/mole/min . g foetal weight, the flux from the foetal to the maternal side was 0 340 + 0-018 ,umole/min. g foetal weight (n = 38). The corresponding p.d. was -20*7 + 1-2 mV (foetal side negative).4. The active component of Na transport across the placenta was calculated from the unidirectional fluxes and the p.d. The active transport was directed from the foetal to the maternal side, and its rate was 0*211 + 0*015 5umole/min. g foetal weight (n = 38). During perfusion ofthe placenta with KCN (10-3 M) the active transport decreased by approximately one third.5. The flux of Na from the foetal to the maternal side of the perfused placenta was higher than the flux from the maternal to the foetal side. A similar asymmetry of Na fluxes was observed in the non-perfused placenta, J. vTULC AND J. 9VIHOVEC the flux from mother to foetus being 0 180 + 0-013,mole/min.g foetal weight and the flux from foetus to mother 0*235+00024 #smole/min.g foetal weight (n = 12). This indicates that the asymmetry of Na fluxes is caused by the anaesthesia and/or by the trauma of the operation rather than by the perfusion of the placenta.6. The permeabilities ofthe perfused placenta to Na and sucrose measured simultaneously from the maternal to the foetal side were 0-0767 + 00183 and 0-0324 + 0 0094 cm3/min (n = 7), respectively. The permeability values bear the same relation to each other as the respective coefficients of free diffusion in water, suggesting that the passive transport of Na across the placenta takes place as simple diffusion through wide aqueous channels.6. The observations of this work are consistent with two different mechanisms of Na transport across the placenta: (1) simple diffusion (presumably bidirectional); and (2) unidirectional active transport from the foetal ...

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The Transplacental Potential Difference in Guinea-Pigs

Cited by 14 publications

References 6 publications

Technique for <i>in situ</i> Perfusion of the Guinea Pig Placenta

Technique for <i>in situ</i> Perfusion of the Guinea Pig Placenta

Permeability of the Foetal Guinea-Pig Placenta to Arginine-Vasopressin

Placental transport of sodium in the guinea‐pig.

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