Renal function in the sheep foetus

Alexander, D. Pauline; Nixon, D. A.; Widdas, W. F.; Wohlzogen, F. X.

doi:10.1113/jphysiol.1958.sp005912

Cited by 89 publications

(41 citation statements)

References 9 publications

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Section: Methodsmentioning

confidence: 99%

“…Tributaries of the umbilical veins and arteries were catheterized for intravenous administrations and blood sampling respectively. Exposure and cannulation of the foetal bladder was carried out in the manner previously described (Alexander, Nixon, Widdas & Wohlzogen, 1958).Two lambs (10 hr and 7 days post-natal), were anaesthetized with intravenous thiopentone, the abdomen opened and the bladder cannulated directly. Catheters were inserted in the femoral vein and artery for administrations and blood sampling.…”

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confidence: 99%

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Reabsorption of glucose, fructose and meso‐inositol by the foetal and post‐natal sheep kidney

Alexander¹,

Nixon²

1963

The Journal of Physiology

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The purpose of the present investigation was to study the excretion by the foetal kidney of the sheep of three normal components of foetal sheep blood, namely glucose, fructose and meso-inositol. Evidence has been put forward that in man these substances share some common element of the reabsorptive mechanism; thus Gammeltoft & Kjerulf-Jensen (1943) have suggested that glucose and fructose compete, while Daughaday & Larner (1954) suggested a common mechanism for glucose and meso-inositol.The results reported here indicate that glucose reabsorption is well established in the foetus by the middle of gestation, whereas fructose and mesoinositol are only poorly reabsorbed. METHODSStudies were made on eight foetuses between 59 and 135 days gestation age. The foetuses were delivered by Caesarian section from Welsh ewes under procaine spinal anaesthesia, supplemented when necessary during the course of the experiment with intravenous thiopentone. The ewe was held in the supine position with the head and upper portion of the trunk elevated to an angle of about 450 above the horizontal. On delivery the foetus was placed on a heated platform fixed between the legs of the ewe. Care was taken to ensure that the cord was not under tension and that it was kept warm and moist. With older foetuses the head was initially delivered into a polythene bag containing 0 9 %O NaCl solution, to prevent the onset of breathing. Tributaries of the umbilical veins and arteries were catheterized for intravenous administrations and blood sampling respectively. Exposure and cannulation of the foetal bladder was carried out in the manner previously described (Alexander, Nixon, Widdas & Wohlzogen, 1958).Two lambs (10 hr and 7 days post-natal), were anaesthetized with intravenous thiopentone, the abdomen opened and the bladder cannulated directly. Catheters were inserted in the femoral vein and artery for administrations and blood sampling.In two adult ewes experiments have been performed under spinal anaesthesia, in which the bladder was either cannulated directly or by the urethral insertion of a catheter. Experiments have also been performed on the unanaesthetized ewes at intervals over several weeks. With aseptic techniques, amethocaine (10-15 mg in 2-5 ml. of 4-5 % glucose) was injected into the subarachnoid space immediately above the sacrum. Long polythene catheters (Allen and Hanbury Ltd., No. 2) fitted with two-way taps were inserted into the dorsalis pedis artery and vein so that the tips lay in the large vessels. The catheters were filled with heparin saline solution (5000 i.u. ml.). After suturing the skin and applying

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Reabsorption of glucose, fructose and meso‐inositol by the foetal and post‐natal sheep kidney

Alexander¹,

Nixon²

1963

The Journal of Physiology

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“…The mean content of PRL in the pituitary gland increased sharply from 14.8±4.6 ng at 15-19 wk to 405±142 ng at 20-24 wk and 542±204 ng at 25-29 wk gestation. By term, the mean content was 2,039± 459 (range 493-3,689) and the mean concentration 15.9±2.4 ng/mg (range [7][8][9][10][11][12][13][14][15][16][17][18][19][20]. There was a significant positive correlation (P < 0.001) between the hPRL and human growth hormone (hGH) content of fetal pituitary glands; at term the hPRL/hGH ratio was 1/290.…”

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The ontogenesis of human fetal hormones. III. Prolactin.

Aubert¹,

Grumbach²,

Kaplan³

1975

J. Clin. Invest.

113

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A B S T R A C T The synthesis and release of human prolactin (hPRL) in the human fetus was assessed by radioimmunoassay analysis of the content and concentration of hPRL in 82 pituitary glands and the concentration of serum hPRL in 47 fetuses of gestational age 68 days to term. Fetal hPRL exhibited parallelism with the reference standard (Lewis 203-1). hPRL was detected by 68 days of gestation (10 wk), the earliest fetal pituitary gland studied; 8 out of 33 pituitaries had a prolactin (PRL) content above 2.0 ng between 10-15 wk gestation. The mean content of PRL in the pituitary gland increased sharply from 14.8±4.6 ng at 15-19 wk to 405±142 ng at 20-24 wk and 542±204 ng at 25-29 wk gestation. By term, the mean content was 2,039± 459 (range 493-3,689) and the mean concentration 15.9±2.4 ng/mg (range 7-20). There was a significant positive correlation (P < 0.001) between the hPRL and human growth hormone (hGH) content of fetal pituitary glands; at term the hPRL/hGH ratio was 1/290. The concentration of serum hPRL between 12 and 24 wk ranged from 2.9 to 67 ng/ml, mean 19.5±2.5 ng/ml (n = 41); by 26 wk fetal serum hPRL increased sharply and attained levels of 300-500 ng/ml in late gestation. At delivery, the mean plasma concentration of hPRL was 167±+14.2 ng/ml in 36 umbilical venous specimens and 111.8±12.3 ng/ml in the matched maternal venous specimens. No correlation between serum hPRL and the pituitary content or concentration of hPRL was demonstrable in 12 matched fetal specimens.In five anencephalic infants, umbilical venous hPRL levels were between 65 and 283 ng/ml. In two anencephalic infants, thyrotropin releasing factor (TRF) (200 Ag IV) evoked a rise in serum hPRL in one patient from 43 to 156 ng/ml at 30 min, and in the other from 65 to Dr. Aubert is recipient of a grant from the Swiss National Fund for Scientific Research.

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“…Early in gestation when the foetus is rapidly developing it is susceptible to undesirable changes in its environment, thus making it necessary for the amnion to be impermeable so that the environment may be closely controlled. As the foetus proceeds towards term it becomes less vulnerable and also more able to control its own environment by kidney and gastric function (Alexander et al 1958;Wright, 1962). The permeability of the amnion to non-electrolytes was, in general, related to their oil/water partition coefficients.…”

Section: Discussionmentioning

confidence: 99%

A study of the transport and permeability properties of the guinea‐pig amniotic membrane.

North¹,

Segal²

1976

The Journal of Physiology

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SUMMARY1. The simultaneous measurement of the two-way sodium flux across the in vitro amniotic epithelium did not reveal a preferential active movement of sodium in either direction. The amnion is thus unlikely to be the site of formation of amniotic fluid.2. The permeability of the amniotic epithelium to some non-electrolytes has been measured with isotopes and was found to be generally low in relation to the thinness of the tissue. The permeability to non-electrolytes would appear to be dependent on the oil/water partition coefficient of the permeating substance.3. The permeability to sodium and to non-electrolytes was found to vary with gestational age. The amnion from animals of 61-70 days' gestation was markedly more permeant than those at 50-60 days (term 70 days).

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Renal function in the sheep foetus

Cited by 89 publications

References 9 publications

Reabsorption of glucose, fructose and meso‐inositol by the foetal and post‐natal sheep kidney

Reabsorption of glucose, fructose and meso‐inositol by the foetal and post‐natal sheep kidney

The ontogenesis of human fetal hormones. III. Prolactin.

A study of the transport and permeability properties of the guinea‐pig amniotic membrane.

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