Effect of Fetal Nephrectomy on Insulin-Like Growth Factors and Their Binding Proteins in Sheep

Iwamoto, Harriet S.; McConnell, Carol

doi:10.1159/000244402

Cited by 2 publications

(3 citation statements)

References 18 publications

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“…The finding that the two groups of foetuses were similar in weight was in agreement with other studies in which foetuses have been nephrectomized late in gestation. 3,5,8,18 In the second part of this study, our aim was to determine which of the changes observed following nephrectomy could be attributed to absence of the foetal RAS. Therefore, the dose of AngII used for the continuous infusion (1.5 g/kg per h) was chosen to provide replacement levels of AngII.…”

Section: Discussionmentioning

confidence: 99%

“…Many workers have reported at least one of these blood gas changes after foetal nephrectomy. 5,6,8,18 The poorer blood gas status after nephrectomy may have been due to several factors. First, the nephrectomized foetuses had lower HR and, therefore, possibly lower cardiac outputs and reduced placental blood flows compared with intact foetuses.…”

Section: Arterial Blood Gasesmentioning

confidence: 99%

“…However, this would not explain blood gas alterations in other studies in which both carotid arteries were left intact. 5,6,8,18…”

Section: Arterial Blood Gasesmentioning

confidence: 99%

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Effects of Bilateral Nephrectomy and Angiotensin Ii Replacement on Body Fluids in Foetal Sheep

Gibson

Lumbers

1999

Clin Exp Pharma Physio

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1. To determine the importance of the kidneys in maintaining the normal volume and composition of foetal body fluids, measurements were made in 11 chronically catheterized foetuses (123-136 days) that had been bilaterally nephrectomized at least 5 days previously and compared with 10 intact foetuses (121-133 days). 2. The nephrectomized foetuses had reduced extracellular (ECV), blood, plasma and interstitial volumes per kg foetal weight (P < 0.005), reduced plasma chloride levels (P < 0.001) and were acidaemic, hypoxaemic and hypercapnaemic (P < 0.05) compared with intact foetuses. They also had reduced lung liquid production (P < 0.05) and reduced lung liquid sodium and osmolality levels (P < 0.05). Their arterial pressure was more variable between foetuses (P < 0.005) and was directly related to ECV/kg (P = 0.013). 3. To determine which of these changes were due to absence of the foetal renin-angiotensin system, seven chronically catheterized nephrectomized foetal sheep (124-132 days) were infused with replacement doses of angiotensin (Ang)II (1.5 micrograms/kg per h) for 3 days. Six nephrectomized foetuses were infused with 0.15 mol/L saline. 4. The AngII infusion was non-pressor. It prevented the fall in ECV that occurred in the control group (P < 0.05) and foetal plasma chloride concentration rose (P < 0.05). Blood gas status and lung liquid production rate did not change, but lung liquid sodium concentration fell (P < 0.05) and potassium concentration rose (P < 0.05). 5. Bolus injections of AngII (0.3-5 micrograms) were given to assess vascular sensitivity to AngII. This was not altered by either nephrectomy or AngII replacement. 6. It is concluded that the foetal kidneys are important for the maintenance of the normal volume and composition of foetal body fluids. Angiotensin II, perhaps because it promotes fluid transfer across the placenta, helps maintain foetal ECV and plasma chloride levels.

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Section: Discussionmentioning

confidence: 99%

Section: Arterial Blood Gasesmentioning

confidence: 99%

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Effects of Bilateral Nephrectomy and Angiotensin Ii Replacement on Body Fluids in Foetal Sheep

Gibson

Lumbers

1999

Clin Exp Pharma Physio

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Glucose and amino acid kinetic response to graded infusion of rhIGF-I in the late gestation ovine fetus

Liechty

Boyle

Moorehead

et al. 1999

American Journal of Physiology-Endocrinology and Metabolism

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Insulin-like growth factor I (IGF-I) has anabolic effects and is thought to be important in fetal development. The present study was designed to determine the dose response of recombinant human (rh) IGF-I on ovine fetal glucose and amino acid kinetics. Chronically catheterized fetal lambs were studied at 122–127 days gestation. The kinetics of leucine, phenylalanine, and glucose were measured before and during the infusion of rhIGF-I. rhIGF-I was infused into the fetal inferior vena cava at low, medium, or high rates (9.9, 20.1, or 40.2 nmol/h, respectively). A stepwise increase in serum IGF-I was achieved (164 ± 3, 222 ± 7, and 275 ± 5 ng/ml). Insulin concentrations were decreased at the medium and high rhIGF doses. The rate of appearance (Ra) of leucine and phenylalanine and leucine oxidation decreased. Phenylalanine appearance from protein breakdown was decreased, with a maximal suppression of 30% observed at the highest rate of infusion. Glucose Ra was increased at the medium and high doses; other aspects of glucose metabolism were unchanged. The change in both glucose Ra and suppression of proteolysis was significantly correlated to the rhIGF-I infusion rate. It is concluded that rhIGF-I exerts dose-related effects in the ovine fetus, increasing fetoplacental glucose turnover and causing significant suppression of both proteolysis and amino acid oxidation.

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Effect of Fetal Nephrectomy on Insulin-Like Growth Factors and Their Binding Proteins in Sheep

Cited by 2 publications

References 18 publications

Effects of Bilateral Nephrectomy and Angiotensin Ii Replacement on Body Fluids in Foetal Sheep

Effects of Bilateral Nephrectomy and Angiotensin Ii Replacement on Body Fluids in Foetal Sheep

Glucose and amino acid kinetic response to graded infusion of rhIGF-I in the late gestation ovine fetus

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