Studies of renal function in the intact fetal lamb

Smith, F.; Adams, Forrest H.; Borden, Margaret; Hilburn, Jean M.

doi:10.1016/0002-9378(66)90321-8

Cited by 31 publications

(12 citation statements)

References 9 publications

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“…After a longitudinal incision in the cord, the urachus was identified as a small tubular structure surrounded by a distinct vascular plexus. 5,6,7,9,10) or allantoic sac (animals M, 1, 2, 4). The uterus and fetal membranes were closed as previously described.…”

Section: Methodsmentioning

confidence: 99%

“…These measurements have been limited to the time period during surgery or to a few hours after the operation. In the sheep fetus older than 115 days gestational age, estimates of glomerular filtration rate (GFR)' have ranged from 0.2 to 1.4 ml/min * kg body weight and urine osmolalities from 60 to 600 mOsm/kg H20 (7)(8)(9)(10)(11). It is not clear whether these wide ranges observed represent normal variability between animals or are, somehow, the product of abnormal experimental conditions.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

An Evaluation of Fetal Renal Function in a Chronic Sheep Preparation

Gresham¹,

Rankin²,

Makowski³

et al. 1972

J. Clin. Invest.

119

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A B S T R A C T Fetal renal function in the sheep was investigated in a chronic preparation which permitted repeated evaluations of urine flow and osmolality as well as renal clearances in animals which were unanesthetized and remote from acute surgical stress. Measurements of fetal blood pressure, pH, osmolality, fetal growth in utero, and final outcome did not indicate an adverse effect of the experimental procedure on the fetus.Fetal urine flow and osmolality were highly variable during the early postoperative period. They did not stabilize until 3-6 days after surgery, when urine osmolality became markedly hypotonic (range 65-160 mOsm/ kg H20) and urine flow rose to approximately 0.14 ml/min kg. Fluctuations in urine flow and osmolality in the early postoperative period were the result of tubular reabsorption of water rather than a change in the glomerular filtration rate.The inulin-"4C clearance, used as a measure of the glomerular filtration rate, was 1.05 ±0.05 ml/min -kg (mean +SEM) for all animals studied. Urea, fructose, sodium, and chloride were partially reabsorbed by the fetal kidney, while creatinine was secreted.Continuous drainage of fetal urine for 18 days in one animal demonstrated that the fetus was able to excrete large amounts of water, sodium, and fructose without apparent detrimental effects.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An Evaluation of Fetal Renal Function in a Chronic Sheep Preparation

Gresham¹,

Rankin²,

Makowski³

et al. 1972

J. Clin. Invest.

119

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“…Based on work in which fetal serum calcium was lowered, either after removal of the fetal parathyroid gland by decapitation in utero (24), or following the injection into rat fetuses of guinea-pig antiserum to rat parathyroid hormone (12), it was suggested that fetal parathyroid hormone plays a role in maintaining the level of calcium in the fetus. Although the parathyroid gland of the fetus has been shown to be functional before birth (21,28,32), the fact that in fetal life, renal phosphate clearance is low (11,29) but increases in response to exogenous parathyroid hormone (30), and the finding that following birth, in the face of falling concentrations of calcium, circulating levels of parathyroid hormone are also low or undetectable (7,10,34), lend support to the belief that the high levels of circulating calcium in utero result in suppression of fetal parathyroid gland activity.…”

Section: Discussionmentioning

confidence: 99%

pH and the Level of Calcium in the Blood of Fetal and Neonatal Albino Rats

Krukowski¹,

Smith²

1976

Neonatology

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Near-term rat fetuses in utero are acidotic and hypoxic, and have high levels of total serum calcium. In the first hour of postnatal life, pO₂ and pH increase and pCO₂ and calcium fall. Between 1 and 4 h following birth, respiratory gases vary little, whereas pH continues to rise and calcium further declines. By 4 h, newborns reach normal pH levels but are markedly hypocalcemic. It is suggested that the Ê»hypercalcemia’ of intrauterine life is related to acidosis in utero, and that following birth, the initial fall in serum calcium is associated with the blowing off of CO₂ and a concomitant rise in pH. The later decline in circulating calcium is independent of alterations in respiratory gases and relates directly to the final correction of neonatal acidosis.

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“…Such patterns would be consistent with the suggestion that fetal urine is a source of agalactosidase and /Y-acetyl-ß-hexosaminidase activities and that sheep fetal urine is first accumulated in the allantoic sac via the urachus up to a gestational age of 86-90 days and thereafter passes more and more into the amniotic sac. This is thought to be due to the occlusion of the urachus and increasing potency of the urethra (Smith et al, 1966;Mellor & Slater, 1971. The protein concentration also followed a similar pattern being about 6-fold more elevated in allantoic than in amniotic fluid at 49-65 days and reaching approximately equal concentrations in both sacs at 106-132 days.…”

Section: Discussionmentioning

confidence: 79%

“…Evidence has been found that the human fetus releases its intestinal content into the amniotic cavity: Benzie & Doran (1975), using a special endoscope, observed fetal defaecation in utero in an 18-week fetus, and the presence of intestinal disaccharidases (Potier et al, 1975(Potier et al, , 1976 and biliary salts (Délèze, Sidiropoulos & Paumgartner, 1977) has been reported in amniotic fluid. The pregnant ewe is particularly useful for study of the origin of amniotic fluid enzymes because the fetal urine is apparently accumulated in the allantoic cavity early in gestation (Smith, Adams, Borden & Hilburn, 1966;Mellor & Slater, 1971 while intestinal enzymes are extruded in the amniotic cavity.…”

Section: Introductionmentioning

confidence: 99%

Origin and developmental patterns of lactase and other glycosidases in sheep amniotic and allantoic fluid

Potier¹,

Guay²,

Lamothe³

et al. 1979

Reproduction

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Summary. Intestinal lactase activity (with its associated cellobiase, 4\ x=r eq-\ methylumbelliferyl-\g=b\-galactosidase and -\g=b\-glucosidaseactivities) was used as a specific intestinal marker enzyme to study the release of protein and enzymes of intestinal origin in sheep amniotic fluid during gestation. In amniotic fluid, intestinal lactase activity peaked at 66\p=n-\85days of gestation and then decreased with gestation. This enzyme activity was very low or absent in allantoic fluid throughout gestation suggesting that there is no important transfer of amniotic fluid lactase towards the allantoic cavity. Maltase and 4-methylumbelliferyl-\g=a\-glucosidase showed no statistically significant variation with gestation in both amniotic and allantoic fluid whereas \g=a\-galactosidase and N-acetyl-\g=b\-hexosaminidase which were first higher in allantoic than in amniotic fluid increased in amniotic fluid to reach allantoic fluid levels near term. Such patterns are consistent with the suggestion that the fetal urine is a source of \g=a\-galactosidase and N-acetyl-\g=b\-hexosaminidase activities and that sheep urine is first accumulated in the allantoic sac via the urachus up to 86\p=n-\90 days of gestation and thereafter passes more and more into the amniotic sac.

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Studies of renal function in the intact fetal lamb

Cited by 31 publications

References 9 publications

An Evaluation of Fetal Renal Function in a Chronic Sheep Preparation

An Evaluation of Fetal Renal Function in a Chronic Sheep Preparation

pH and the Level of Calcium in the Blood of Fetal and Neonatal Albino Rats

Origin and developmental patterns of lactase and other glycosidases in sheep amniotic and allantoic fluid

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