This thesis reports the effects of an altered intrauterine environment on the offspring???s renal, cardiovascular and renin angiotensin systems. After a midgestational asphyxial episode in fetal sheep (30 min total umbilical cord occlusion at 90 days; term 150 days) the hydrops that resulted had not completely resolved by 130 days. While the heart and kidneys were apparently unaffected, the brain and lung weights were 37% and 50% lower than sham values, respectively and there were joint contractures. The effects of maternal renal disease on the offspring were investigated. Although in utero fetuses of subtotally nephrectomised ewes (STNx) had altered urine flow rates, sodium excretion, haematocrits, plasma chloride and plasma renin levels, by 1-2 weeks after birth these values in the lambs (STNxL) were similar to controls (ConL) under baseline conditions. Body weight and the weights of most organs were similar, including the kidney, in which glomerular number was normal. In the neonatal period, the lambs were subjected to four challenges: furosemide (2 mg/kg intravenous bolus), infusion of angiotensin II and phenylephrine, intravenous infusion of 0.15M saline (50 ml/kg over 30 min) and haemorrhage (20% estimated blood volume over 10 min). These challenges revealed evidence of programming of several aspects of the renal, cardiovascular and renin angiotensin systems in the STNx offspring. As young adults at 6 months of age, male and female offspring of STNx ewes were normotensive and had normal renal function. On a high salt diet (HSD, 0.17M NaCl in 8L water for 5-7days), female offspring of both groups did not become hypertensive. However, the STNx offspring must have retained salt and water as plasma sodium was increased and haematocrit was decreased. In the STNx offspring only, there was a relationship between glomerular filtration rate (GFR) and mean arterial pressure, indicating an inability to maintain a constant GFR in response to changes in arterial pressure.
| Identifer | oai:union.ndltd.org:ADTP/257208 |
| Date | January 2006 |
| Creators | O???Connell, Amanda Elizabeth, School of Medical Science, UNSW |
| Publisher | Awarded by:University of New South Wales. School of Medical Science |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Copyright Amanda Elizabeth O???Connell, http://unsworks.unsw.edu.au/copyright |
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