Maternal renal dysfunction in sheep is associated with salt insensitivity in female offspring.

To examine the programming effects of maternal renal dysfunction (created by subtotal nephrectomy in ewes prior to mating; STNx), renal and cardiovascular function were studied in 6-month-old male and female offspring of STNx and control pregnancies. After studies were conducted on a low salt diet (LSD) some female offspring underwent salt loading (0.17 M NaCl in the drinking water for 5-7 days; HSD). On LSD both male and female offspring of STNx had similar mean arterial pressures (MAP), heart rates, cardiac outputs and renal function to those measured in offspring of control ewes. In female STNx offspring on a HSD, plasma sodium levels increased and haematocrits fell, indicating volume expansion (P < 0.05). Plasma renin levels were not suppressed despite the increases in plasma sodium concentrations, but aldosterone levels were reduced. In control animals plasma renin levels fell (P < 0.05) but there was no change in plasma aldosterone concentrations. There was a positive relationship between GFR and MAP which was present only in female STNx offspring. In conclusion, in STNx offspring there was an impaired ability to regulate glomerular filtration independent of arterial pressure, renin release was insensitive to a high salt intake and control of aldosterone secretion was abnormal. This study provides evidence of abnormal programming of the renin-angiotensin system and glomerular function in offspring of pregnancies in which there is impaired maternal renal function.

Pregnancy stress, healthy pregnancy and birth outcomes - the need for early preventative approaches in pregnant Australian Indigenous women: a prospective longitudinal cohort study.

Adverse pregnancy outcomes including prematurity and low birth weight (LBW) have been associated with life-long chronic disease risk for the infant. Stress during pregnancy increases the risk of adverse pregnancy outcomes. Many studies have reported the incidence of adverse pregnancy outcomes in Indigenous populations and a smaller number of studies have measured rates of stress and depression in these populations. This study sought to examine the potential association between stress during pregnancy and the rate of adverse pregnancy outcomes in Australian Indigenous women residing in rural and remote communities in New South Wales. This study found a higher rate of post-traumatic stress disorder, depression and anxiety symptoms during pregnancy than the general population. There was also a higher incidence of prematurity and LBW deliveries. Unfortunately, missing post-traumatic stress disorder and depressive symptomatology data impeded the examination of associations of interest. This was largely due to the highly sensitive nature of the issues under investigation, and the need to ensure adequate levels of trust between Indigenous women and research staff before disclosure and recording of sensitive research data. We were unable to demonstrate a significant association between the level of stress and the incidence of adverse pregnancy outcomes at this stage. We recommend this longitudinal study continue until complete data sets are available. Future research in this area should ensure prioritization of building trust in participants and overestimating sample size to ensure no undue pressure is placed upon an already stressed participant.

Influence of maternal adiposity, preterm birth and birth weight centiles on early childhood obesity in an Indigenous Australian pregnancy-through-to-early-childhood cohort study.

Childhood obesity rates are higher among Indigenous compared with non-Indigenous Australian children. It has been hypothesized that early-life influences beginning with the intrauterine environment predict the development of obesity in the offspring. The aim of this paper was to assess, in 227 mother-child dyads from the Gomeroi gaaynggal cohort, associations between prematurity, Gestation Related-Optimal Weight (GROW) centiles, maternal adiposity (percentage body fat, visceral fat area), maternal non-fasting plasma glucose levels (measured at mean gestational age of 23.1 weeks) and offspring BMI and adiposity (abdominal circumference, subscapular skinfold thickness) in early childhood (mean age 23.4 months). Maternal non-fasting plasma glucose concentrations were positively associated with infant birth weight (P=0.005) and GROW customized birth weight centiles (P=0.008). There was a significant association between maternal percentage body fat (P=0.02) and visceral fat area (P=0.00) with infant body weight in early childhood. Body mass index (BMI) in early childhood was significantly higher in offspring born preterm compared with those born at term (P=0.03). GROW customized birth weight centiles was significantly associated with body weight (P=0.01), BMI (P=0.007) and abdominal circumference (P=0.039) at early childhood. Our findings suggest that being born preterm, large for gestational age or exposed to an obesogenic intrauterine environment and higher maternal non-fasting plasma glucose concentrations are associated with increased obesity risk in early childhood. Future strategies should aim to reduce the prevalence of overweight/obesity in women of child-bearing age and emphasize the importance of optimal glycemia during pregnancy, particularly in Indigenous women.

A cohort of Indigenous Australian women and their children through pregnancy and beyond: the Gomeroi gaaynggal study.

Indigenous Australians have high rates of chronic diseases, the causes of which are complex and include social and environmental determinants. Early experiences in utero may also predispose to later-life disease development. The Gomeroi gaaynggal study was established to explore intrauterine origins of renal disease, diabetes and growth in order to inform the development of health programmes for Indigenous Australian women and children. Pregnant women are recruited from antenatal clinics in Tamworth, Newcastle and Walgett, New South Wales, Australia, by Indigenous research assistants. Measures are collected at three time points in pregnancy and from women and their children at up to eight time points in the child's first 5 years. Measures of fetal renal development and function include ultrasound and biochemical biomarkers. Dietary intake, infant feeding and anthropometric measurements are collected. Standardized procedures and validated tools are used where available. Since 2010 the study has recruited over 230 women, and retained 66 postpartum. Recruitment is ongoing, and Gomeroi gaaynggal is currently the largest Indigenous pregnancy-through-early-childhood cohort internationally. Baseline median gestational age was 39.1 weeks (31.5-43.2, n=110), median birth weight was 3180 g (910-5430 g, n=110). Over one third (39.3%) of infants were admitted to special care or neonatal nursery. Nearly half of mothers (47.5%) reported tobacco smoking during pregnancy. Results of the study will contribute to knowledge about origins of chronic disease in Indigenous Australians and nutrition and growth of women and their offspring during pregnancy and postpartum. Study strengths include employment and capacity-building of Indigenous staff and the complementary ArtsHealth programme.

Comparison of the transplacental transfer of enalapril, captopril and losartan in sheep.

1. The transplacental transfers of three drugs (enalapril, captopril and losartan) which block the renin angiotensin system and have different lipophilicities were studied in chronically catheterized foetal sheep (125-139 days gestation). 2. The ability of the foeto-placental unit to convert enalapril to enalaprilat was studied in two chronically catheterized foetuses. Enalapril (3 mg kg-1, 7.9 mumol kg-1) given i.v. to the foetuses abolished the foetal pressor response to 5 micrograms angiotensin I (AI) in one foetus and attenuated the pressor response in the other. 3. Enalapril (100 mg, 5.7 mumol kg-1) given i.v. to the ewe (n = 5) abolished the maternal pressor response to 2.5 micrograms AI (n = 1) and attenuated the maternal pressor response to 5 micrograms AI (n = 5, P < 0.001). The foetal pressor response to 5 micrograms AI (n = 2) and 10 micrograms AI (n = 3) did not change. The maternal and foetal pressor responses to angiotensin II (AII; n = 5) did not change. 4. Foetal pressor responses to 5 micrograms AI (n = 1) and 10 micrograms AI (n = 2) were attenuated within 11 min of their mothers (n = 3) being given i.v. captopril (15 mg, 1.5 mumol kg-1). Foetal pressor responses to 5 micrograms AII (n = 1) and to 10 micrograms AII (n = 2) did not change. 5. Losartan (100 mg, kg-1, 21.7 mumol kg-1) given i.v. to the foetus (n = 9) attenuated the foetal pressor response to 5 micrograms AII (P < 0.001) but the maternal pressor response to 5 micrograms AII did not change. 6. Losartan (100 mg, 21.7 MICROmol kg-1) given i.v. to the ewe (n = 5) attenuated the maternal pressor response to 5 microg AII (P <0.002) but the foetal pressor response to 5 microg AII did not change.7. It is concluded that the foeto-placental unit of the sheep can metabolize enalapril to enalaprilat.Captopril readily crosses the sheep placenta but enalapril and losartan do not. Thus, the transplacental transfer of these drugs does not parallel their lipid solubilities. Furthermore the results show that AT1 receptors are important in mediating the vasoconstrictor effects of AII in the foetus.

The effects of a converting enzyme inhibitor (captopril) and angiotensin II on fetal renal function.

1. Renal function was studied in chronically catheterized fetal sheep (119-128 days gestation), before and during treatment of the ewe with the angiotensin converting enzyme (ACE) inhibitor, captopril, which crosses the placenta and blocks the fetal renin angiotensin system. 2. An i.v. dose of 15 mg (about 319 micrograms kg-1) of captopril to salt-replete ewes followed by an infusion to the ewe of 6 mg h-1 (about 128 micrograms kg-1 h-1) caused a fall in fetal arterial pressure (P < 0.01), and a rise in fetal renal blood flow (RBF) from 67.9 +/- 5.6 to 84.9 +/- 8.3 ml min-1 (mean +/- s.e. mean) (P < 0.05). Renal vascular resistance and glomerular filtration rate (GFR) fell (P < 0.01); fetal urine flow (P < 0.01); fetal urine flow (P < 0.01) and sodium excretion declined (P < 0.05). 3. Ewes were treated for the next 2 days with 15 mg captopril twice daily. On the 4th day, 15 mg was given to the ewe and fetal renal function studied for 2 h during the infusion of captopril (6 mg h-1) to the ewe. Of the 9 surviving fetuses, 3 were anuric and 3 had low urine flow rates. When 6 micrograms kg-1 h-1 of angiotensin II was infused directly into the fetus RBF fell from 69 +/- 10.1 ml min-1 to 31 +/- 13.9 ml min-1, GFR rose (P < 0.05) and urine flow (P < 0.01) and sodium excretion increased in all fetuses. 4. It is concluded that the small fall in fetal arterial pressure partly contributed to the fall in fetal GFR but in addition, efferent arteriolar tone fell so that the filtration pressure fell further. Thus maintenance of fetal renal function depends on the integrity of the fetal renin angiotensin system. These findings explain why use of ACE inhibitors in human pregnancy is associated with neonatal anuria.

Angiotensin and aldosterone.

The object of this review is to describe the role of the renin-angiotensin system in control of aldosterone secretion. The review focuses on the roles of the circulating renin-angiotensin (RAS) system, the activity of which is determined predominantly by control of renin secretion from the kidney and on the role of the intra-adrenal RAS. Angiotensin can bind to two types of G protein coupled receptors, the AT1 and AT2 receptors. Both receptors are found on cells from the zona glomerulosa, the site of aldosterone synthesis. Angiotensin II acting via the AT1 receptor stimulates the synthesis of aldosterone at early and late steps in the pathway. Its effect on aldosterone is influenced by a number of other factors such as plasma potassium levels, sodium status, other peptides such as ANP and adrenomedullin and proadrenomedullin N-terminal peptide. All components of the RAS are found in the adrenal gland. The activity of this intra-adrenal RAS is unmasked and amplified in nephrectomised animals. Aldosterone controls sodium transport across epithelial cells, but recently novel effects on the heart have been described.

Selective down-regulation of AT2 receptors in uterine arteries from pregnant ewes given 24-h intravenous infusions of angiotensin II.

Previously, we showed that uterine arteries from late gestation pregnant ewes infused intravenously with angiotensin II (Ang II) for 24 h, displayed heightened responsiveness to Ang II in vitro. Furthermore, we found that a small population of ewes with a "preeclampsia-like" disorder also displayed this. Therefore, we have investigated the density and affinity of Ang II receptor subtypes in the uterine arteries from these groups. Ang II receptor binding was measured using 125I [Sar1Ile8] Ang II. Proportions of AT1 and AT2 receptors were determined by inhibiting 125I [Sar1Ile8] Ang II with losartan (AT1 antagonist) or PD 123319 (AT2 antagonist). Uterine arteries from 24-h Ang II-infused ewes had a lower proportion of AT2 receptors (56.2+/-2.3%) than control (saline-infused) ewes (84.1+/-1.0%; P<0.05). The density of AT2 receptors was reduced (P<0.05) while the density of AT1 receptors was not different. Thus, 24-h infusions of Ang II selectively down-regulated AT2 receptors in the uterine artery, resulting in heightened Ang II reactivity. By contrast, the binding properties of Ang II receptor subtypes in uterine arteries from ewes with the "preeclampsia-like" disorder were not different from control ewes.

Angiotensin receptor subtypes in the uterine artery during ovine pregnancy.

This study was undertaken to determine if changes in receptor density or affinity could account for the reduced vascular sensitivity to angiotensin II seen during pregnancy. Angiotensin receptor subtypes in the uterine arteries of non-pregnant, pregnant and postpartum ewes were investigated using saturation and competition receptor binding techniques with the specific receptor antagonists, losartan (DuP-753) and PD-123319 (S)1-[[4-(dimethylamino)-3-methylphenyl]-methyl]-5-(diphenylacetyl )-4,5,6,7-tetrahydro-1H-imidazo(4,5-c)pyridine-6-carboxylic acid, ditrifluoroacetate, monohydrate). Receptor density and affinity of total angiotensin receptors, as well as the angiotensin AT1 and AT2 receptor subtypes in uterine arteries were compared with those in the mesenteric artery and aorta. The uterine artery contains both AT1 and AT2 receptor subtypes, whereas the mesenteric artery and aorta contain primarily the AT1 receptor subtype. In uterine arteries from pregnant sheep, angiotensin receptor density was increased because AT2 receptors were increased. AT1 receptor density was not altered. This change was not seen in the aorta. In the uterine artery, receptor affinity for [Sar1,Ile8]angiotensin II decreased in mid-gestation (IC50 7.7 +/- 1.2 x 10(-9) M) compared with non-pregnant ewes (IC50 3.0 +/- 0.6 x 10(-9) M, P = 0.006), and there was decreased affinity of angiotensin AT1 receptors for losartan during pregnancy (IC50 2.8 +/- 1.0 x 10(-4) M) compared with non-pregnant ewes (IC50 2.2 +/- 1.3 x 10(-6) M, P = 0.025). Our results show changes in the density and affinity of the angiotensin receptor subtypes in the uterine artery which could explain its reduced responsiveness to circulating angiotensin II during pregnancy.

Effect of cortisol on fetal ovine vascular angiotensin II receptors and contractility.

The renin angiotensin system is important in the regulation of fetal blood pressure. This study investigated the expression of angiotensin AT(1) and AT(2) receptors in the ovine fetal heart, aorta and umbilical artery, and how these receptors are affected by cortisol. Cortisol infusion into the fetus has previously been shown to cause an increase in fetal blood pressure. We hypothesised that this effect of cortisol is mediated by upregulation of the angiotensin AT(1) receptor. Binding studies performed on tissues with intact endothelium demonstrated both receptor subtypes in the fetal aorta and right ventricle, although the latter contained mainly angiotensin AT(2) receptors. In contrast, only angiotensin AT(1) receptors were found in the umbilical artery. Cortisol infusion into fetuses (3 mg/day for 3-5 days) caused a physiological increase in plasma cortisol levels to 29+/-4 nM. This was associated with an increase in systolic pressure (57.8+/-1.7 vs. 52.2+/-1.5 mm Hg, P<0.05), but cortisol had no effect on the density or affinity of angiotensin receptors, nor on the in vitro contractile responses of carotid and umbilical arterial rings to 5-microM angiotensin II. In conclusion, this study has demonstrated differential expression of angiotensin AT(1) and AT(2) receptors in the different regions of the ovine fetal cardiovascular system and that the angiotensin AT(1) receptor is functional. The lack of any effect of low doses of cortisol on these receptors and on the contractility of isolated fetal vessels to angiotensin II suggests cortisol acts by other mechanisms to raise fetal arterial pressure.

Interactions between AT1 and AT2 receptors in uterine arteries from pregnant ewes.

This study was performed to investigate the roles of angiotensin receptors (AT1 and AT2) in the contractility of uterine arteries during normal pregnancy and after angiotensin II levels have been elevated. Pregnant ewes were given intravenous infusions of saline for 24 h (control) or angiotensin II (30 ng kg(-1) min(-1)) for 2 or 24 h. The contractile responses of uterine arterial rings to angiotensin II (4 microM) and antagonists were then examined in vitro. Most uterine arteries were relatively insensitive to the vasoconstrictor effects of angiotensin II. In rings from control ewes an angiotensin AT2 antagonist enhanced (P < 0.05) the contractile responses to angiotensin II, suggesting that angiotensin AT2 receptors inhibited the angiotensin AT1 receptor mediated contractions. Uterine arterial rings from ewes given intravenous infusions of angiotensin II displayed greater (P < 0.05) contractile responses to angiotensin II in vitro compared to rings from control ewes. This was in part due to down regulation of angiotensin AT2 receptors. Surprisingly, while performing these experiments a small number of ewes had uterine arteries which were "hyperreactive" to angiotensin II (contractile responses 6-fold greater). These ewes also had abnormal renin angiotensin systems and had some features which are characteristic of those seen in preeclampsia. The "hyperreactivity" of these arteries could only in part be explained by down regulation of angiotensin AT2 receptors. It is concluded that in normal pregnancy angiotensin AT2 receptors play a role in maintaining an adequate uterine blood flow for the fetus. When angiotensin II levels are elevated for a prolonged period this protective effect is lost partly because angiotensin AT1 receptors are down regulated.

Development of renal function in the fetus: a review.

This review concentrated mainly on studies of intrauterine renal function carried out in chronically-catheterized fetal sheep. In sheep, as in primates, nephrogenesis is complete before birth. Studies in the rat and neonatal puppy provide insight into the functional development of the kidney, because these species are immature at birth and there is considerable postnatal renal development. Studies of the ovine fetus provide insight into the physiological role(s) of the kidneys during intrauterine life, albeit modified by changes related to maturation.

Effects of changes in colloid osmotic pressure on excretion of sodium by the ovine fetal kidney.

To find out if the gestation-dependent increase in fetal oncotic pressure is responsible for the gestation-dependent increase in the capacity of the fetal proximal tubule to reabsorb sodium, the effects on renal function of increases in oncotic pressure were studied in 8 volume-expanded chronically catheterized fetal sheep aged 128 +/- 3 (s.e.) days. Fetal extracellular volume was expanded by infusion of 65 +/- 10.8 (s.e.) mliter kg-1 estimated body weight of 0-15 M saline. This caused a decrease in fetal plasma protein concentrations (P < 0.01); fetal oncotic pressure decreased (P < 0.05). A diuresis and natriuresis occurred, which was due not to an increase in glomerular filtration rate but to a decrease in the fraction of the filtered sodium load reabsorbed by the proximal tubule (P < 0.05) and a decrease in the fraction of distally delivered sodium reabsorbed (P < 0.01). Fetal plasma protein concentrations were then increased to greater than control levels (P < 0.01) by infusion of maternal plasma (28 +/- 1.6 mliter kg-1); oncotic pressure was greater than after saline expansion (P < 0.05) and similar to control. The fraction of the filtered sodium load reabsorbed by the proximal tubule remained depressed (P < 0.01) relative to control, as did the fraction of distally delivered sodium that was reabsorbed (P < 0.01). Thus the natriuresis and diuresis continued. There was, however, a small effect of oncotic pressure on proximal fractional sodium reabsorption that was unmasked by multiple regression analysis. Obviously, this effect was not sufficient to override other effects of volume expansion on fetal proximal tubular function. Therefore, the reduction in fetal proximal fractional sodium reabsorption in volume expansion was not due solely to a fall in fetal oncotic pressure. Furthermore, since infusion of maternal plasma caused a rise in fetal plasma protein concentrations that was similar to the increase that would occur between 128 and 148 days gestation, it is unlikely that any gestation-dependent increase in proximal fractional sodium reabsorption is due solely to the increase in fetal plasma protein concentrations and hence oncotic pressure.

Gestational changes in fetal renal and hepatic angiotensinogen mRNA and protein.

The aim of the study was to determine the amount of angiotensinogen expression and its protein product in fetal sheep liver and kidney in the last third of gestation. Angiotensinogen mRNA was measured by RNase protection assay and its protein levels were measured by radioimmunoassay. Levels were measured at 80, 95, 111, 125 and 139 days. Angiotensinogen mRNA was present in all fetal liver and kidney samples tested. The ratio of hepatic angiotensinogen mRNA/18 S rRNA increased by 100% (P < 0.001) and angiotensinogen levels increased by 33% (P < 0.001) in fetal sheep from 80 to 139 d. Over the same period the ratio of renal angiotensinogen mRNA/18 S rRNA increased by 170% (P < 0.001) and renal angiotensinogen protein increased by 41% (P < 0.001). The levels of angiotensinogen mRNA and its protein in the adult kidney were less than in kidneys of 139 d old fetuses (P < 0.01). There was a direct relationship between levels of angiotensinogen mRNA and its protein in the liver (r = 0.53, P < 0.01, n = 25) and in the kidney (r = 0.75, P < 0.0001, n = 24). These findings demonstrate that there is a significant increase in both hepatic and renal angiotensinogen gene expression in the last third of gestation in the fetal sheep and that this increase is associated with an increase of angiotensinogen levels in both tissues. This increase in angiotensinogen in late gestation could influence the activity of both the intrarenal and circulating renin angiotensin systems.

The effect of ethanol on habituation and the cardiovascular response to stimulation in fetal sheep.

Fetal cardiovascular (CVS) changes, forelimb movements (FM) and rates of habituation to repeated stimulation, with suffusions of cold saline over the skin, were measured in 12 chronically catheterized fetal sheep aged 130-145 days. Stimulation of the fetuses caused a significant rise in heart rate (HR) (p less than 0.01) and blood pressure (BP) (p less than 0.001) and FM (p less than 0.01). When the ewe was given an intravenous (i.v.) infusion of ethanol which produced fetal ethanol levels of 87 +/- 1.1 mg/100 ml, the number of spontaneous FM decreased (p less than 0.05). After i.v. ethanol, repeated stimulation of the fetuses still caused an increase in FM (p less than 0.01) and a rise in HR (p less than 0.05) and BP (p less than 0.02) but the fetuses habituated more rapidly (7.25 +/- 1.28 stimuli) compared to control experiments performed prior to (21.5 +/- 3.57 stimuli) or after the ethanol (17.75 +/- 5.83, p less than 0.01). Fetal exposure to low concentrations of ethanol does affect the patterns of response and habituation of the developing fetal central nervous system.

Exercise in pregnancy: physiological basis of exercise prescription for the pregnant woman.

A pregnant woman participated in cycling events in the 2000 Olympics. Recently there was concern about the participation of a pregnant woman in the Australian netball team. More and more women are anxious to pursue sports during their pregnancies and to maintain condition. For the clinician or sports physician caring for women who want to maintain a high-level of physical activity there is no simple exercise prescription. It is probable that continuing exercise by women who are already conditioned will not result in foetal compromise, unless there are hidden or unknown complications of pregnancy. Pregnant women should probably exercise within limits that do not cause severe discomfort and should, as pregnancy progresses, be prepared to moderate the intensity and duration of their exercise programs to avoid risks and injury. It is probably not advisable for women to begin high intensity exercise programs when pregnant, although moderate exercise is beneficial to both mother and baby. The type of activity that is undertaken has to be taken into consideration and in particular the adverse effects of supine activity in late gestation recognised.

Reduced nephron endowment in the neonates of Indigenous Australian peoples.

Rates of chronic kidney disease (CKD) among Indigenous groups in Australia exceed non-Indigenous rates eight-fold. Using kidney volume as a surrogate for nephron number, we carried out a study to determine if Indigenous neonates have a smaller kidney volume (and thus a reduced nephron number) from birth compared with non-Indigenous neonates. We recruited term and preterm neonates (<32 weeks) at a tertiary care neonatal unit over a 12 months period. Preterm neonates were assessed (renal sonography and renal function measurement) at 32 weeks corrected age (CA) and again at 38 weeks CA when blood pressure was also measured. All term neonates were assessed in the first post-natal week, including renal sonography, renal function and blood pressure measurement. The primary outcome measured was total kidney volume (TKV) and estimated glomerular filtration rate (eGFR) was a secondary outcome. Data was available for 44 preterm (11 Indigenous) and 39 term (13 Indigenous) neonates. TKV of Indigenous neonates was significantly lower at 32 weeks [12.0 (2.0) v. 15.4 (5.1) ml; P=0.03] and 38 weeks CA [18.6 (4.0) v. 22.6 (5.9) ml; P=0.04] respectively. Term Indigenous neonates also had smaller kidney volumes compared with non-Indigenous neonates. Despite a smaller kidney volume (and reduced nephron number), Indigenous neonates did not have a significantly lower eGFR. Indigenous neonates achieve similar eGFRs to Non-Indigenous neonates, presumably through a higher single nephron filtration rate. This places Indigenous neonates at a greater risk of long-term kidney damage later in life.

Fetal sex and the circulating renin-angiotensin system during early gestation in women who later develop preeclampsia or gestational hypertension.

There are fetal sex-specific differences in the balance between angiotensin (Ang) II and Ang-(1-7) in the maternal circulation during pregnancy. To determine whether at 15 weeks' gestation plasma levels of Ang II and Ang-(1-7), as well as levels of prorenin and Ang-converting enzyme (ACE), predicted the development of gestational hypertension (GH) or preeclampsia (PreE) and were associated with estimates of fetal and maternal health, women who later developed GH (n=50) or PreE (n=50) were compared with body mass index-matched controls (n=100). Women who subsequently developed PreE or GH had increased Ang-(1-7) levels at 15 weeks' gestation compared with women with normal pregnancies. When separated by fetal sex, this difference was seen only in women carrying a female fetus. Prorenin and ACE concentrations were not useful biomarkers for the prediction of either PreE or GH at 15 weeks' gestation. Women with a male fetus who developed PreE and women who subsequently developed GH had increased blood pressures at 15 weeks' gestation compared with women with normal pregnancies, suggesting that these women were on an early trajectory for the development of hypertension. We propose that measurement of Ang-(1-7) during early gestation could be useful in predicting, those women who will go on to develop new-onset hypertension in pregnancy.

The effects of cyclic AMP, sex steroids and global hypomethylation on the expression of genes controlling the activity of the renin-angiotensin system in placental cell lines.

The placental renin-angiotensin system (RAS) is involved in placentation. We have shown that prorenin mRNA (REN) is expressed in a first trimester trophoblast cell line (HTR-8/SVneo) but not in a choriocarcinoma cell line (BeWo). We attempted to stimulate RAS expression in these cells by cAMP, 5'-aza-2'-deoxycytidine (AZA; an inhibitor of methylation), cAMP and AZA combined, and the sex steroids medroxyprogesterone acetate (MPA) and estradiol-17ß (E(2)) with and without cAMP. RAS mRNAs were measured by qPCR and prorenin concentration in supernatants measured by an ELISA. In HTR-8/SVneo cells, all treatments increased REN expression compared to controls and cAMP + AZA combined was more effective than either treatment alone. Prorenin levels in supernatants were similarly upregulated. In HTR-8/SVneo cells, angiotensinogen (AGT) mRNA expression was increased by MPA + E(2) either with or without cAMP. AGT expression was also significantly increased by AZA. BeWo cells did not express REN or prorenin and it was not inducible with any treatment. AGT expression was significantly increased with AZA, the combination of cAMP + AZA, and MPA + E(2) + cAMP treatments. Since cAMP, AZA, cAMP and AZA combined, or MPA and E(2) with and without cAMP in HTR-8/SVneo cells, a cell line most similar in its RAS expression to the in vivo placenta, these factors may affect placental RAS activity. Surprisingly, these treatments also induced AGT expression in BeWo cells. Whether they are involved in regulating AGT in choriocarcinomas in vivo remains to be determined.

The association of AGTR2 polymorphisms with preeclampsia and uterine artery bilateral notching is modulated by maternal BMI.

INTRODUCTION: This study aimed to determine the association of AGTR1 and AGTR2 polymorphisms with preeclampsia and whether these are affected by environmental factors and fetal sex. METHODS: Overall 3234 healthy nulliparous women, their partners and babies were recruited prospectively to the SCOPE study in Adelaide and Auckland. Data analyses were confined to 2121 Caucasian parent-infant trios, among whom 123 had preeclamptic pregnancies. 1185 uncomplicated pregnancies served as controls. DNA was extracted from buffy coats and genotyped by utilizing the Sequenom MassARRAY system. Doppler sonography on the uterine arteries was performed at 20 weeks' gestation. RESULTS: Four polymorphisms in AGTR1 and AGTR2 genes, including AGTR1 A1166C, AGTR2 C4599A, AGTR2 A1675G and AGTR2 T1134C, were selected and significant associations were predominately observed for AGTR2 C4599A. When the cohort was stratified by maternal BMI, in women with BMI ≥ 25 kg/m(2), the AGTR2 C4599A AA genotype in mothers and neonates was associated with an increased risk for preeclampsia compared with the CC genotype [adjusted OR 2.1 (95% CI 1.0-4.2) and adjusted OR 3.0 (95% CI 1.4-6.4), respectively]. In the same subset of women, paternal AGTR2 C4599A A allele was associated with an increased risk for preeclampsia and uterine artery bilateral notching at 20 weeks' gestation compared with the C allele [adjusted OR 1.9 (95% CI 1.1-3.3) and adjusted OR 2.1 (95% CI 1.3-3.4), respectively]. CONCLUSION: AGTR2 C4599A in mothers, fathers and babies was associated with preeclampsia and this association was only apparent in pregnancies in which the women had a BMI ≥ 25 kg/m(2), suggesting a gene-environment interaction.