Experimentally, a typical ∼2-min cord clamp-to-ventilation interval in preterm lambs is accompanied by increased hemodynamic lability of the birth transition. However, whether this lability is related to development of asphyxia after cord clamping, or can be avoided with a shorter clamp-to-ventilation interval, is unknown. To address these questions, anesthetized preterm fetal lambs (gestation 127 ± 2 days) were instrumented with ductus arteriosus and left pulmonary artery flow probes to obtain right ventricular (RV) output, brachiocephalic trunk and aortic isthmus flow probes to measure left ventricular (LV) output, and aortic trunk catheters for pressure measurement and blood gas analysis. With hemodynamics recorded continuously, fetuses were delivered onto the ewe's abdomen and the cord clamped for 1.5 min before ventilation (n = 8), with aortic sampling at 15, 30, 45, and 60 s, or for 0.5 min, with sampling at 15 s (n = 4). With 1.5-min cord clamping, an asphyxial state (Po2 < 10 mmHg) was evident at ≥45 s, with bradycardia and marked falls in LV and RV outputs (by 60% and 50%, P < 0.001), followed after ventilation onset by tachycardia and LV and RV output surges (4- and 3-fold, P < 0.001). By contrast, heart rate and outputs remained stable after 0.5-min cord clamping, with no postventilation change in heart rate or RV output, and a lesser rise in LV output (22%, P < 0.005). In preterm lambs, rapid development of an asphyxial state within 45 s in the cord clamp-to-ventilation interval increased hemodynamic lability of the birth transition, which was reduced with a shorter (∼0.5 min) cord clamp-to-ventilation interval.

Little is known about the effects of fetal ethanol exposure on lung development. Our aim was to determine the effects of repeated ethanol exposure during late gestation on fetal lung growth, maturation, and inflammatory status. Pregnant ewes were chronically catheterized at 91 days of gestational age (DGA; term ϳ147 days). From 95-133 DGA, ewes were given a 1-h daily infusion of either 0.75 g ethanol/kg (n ϭ 9) or saline (n ϭ 8), with tissue collection at 134 DGA. Fetal lungs were examined for changes in tissue growth, structure, maturation, inflammation, and oxidative stress. Between treatment groups, there were no differences in lung weight, DNA and protein contents, percent proliferating and apoptotic cells, tissue and air-space fractions, alveolar number and mean linear intercept, septal thickness, type-II cell number and elastin content. Ethanol exposure caused a 75% increase in pulmonary collagen I ␣1 mRNA levels (P Ͻ 0.05) and a significant increase in collagen deposition. Surfactant protein (SP)-A and SP-B mRNA levels were approximately one third of control levels following ethanol exposure (P Ͻ 0.05). The mRNA levels of the proinflammatory cytokines interleukin (IL)-1␤ and IL-8 were also lower (P Ͻ 0.05) in ethanol-exposed fetuses compared with controls. Pulmonary malondialdehyde levels tended to be increased (P ϭ 0.07) in ethanolexposed fetuses. Daily exposure of the fetus to ethanol during the last third of gestation alters extracellular matrix deposition and surfactant protein gene expression, which could increase the risk of respiratory distress syndrome after birth. Changes to the innate immune status of the fetus could increase the susceptibility of the neonatal lungs to infection.

Harding R, Moritz KM. Repeated ethanol exposure during late gestation decreases nephron endowment in fetal sheep. Am J Physiol Regul Integr Comp Physiol 295: R568 -R574, 2008. First published June 18, 2008 doi:10.1152/ajpregu.90316.2008.-Maternal alcohol consumption during pregnancy can affect fetal development, but little is known about the effects on the developing kidney. Our objectives were to determine the effects of repeated ethanol exposure during the latter half of gestation on glomerular (nephron) number and expression of key genes involved in renal development or function in the ovine fetal kidney. Pregnant ewes received daily intravenous infusion of ethanol (0.75 g/kg, n ϭ 5) or saline (control, n ϭ 5) over 1 h from 95 to 133 days of gestational age (DGA; term is ϳ147 DGA). Maternal and fetal arterial blood samples were taken before and after the start of the daily ethanol infusions for determination of blood ethanol concentration (BEC). Necropsy was performed at 134 DGA, and fetal kidneys were collected for determination of total glomerular number using the physical disector/fractionator technique; at this gestational age nephrogenesis is completed in sheep. Maximal maternal and fetal BECs of 0.12 Ϯ 0.01 g/dl (mean Ϯ SE) and 0.11 Ϯ 0.01 g/dl, respectively, were reached 1 h after starting maternal ethanol infusions. Ethanol exposure had no effect on fetal body weight, kidney weight, or the gene expression of members of the renin-angiotensin system, insulin-like growth factors, and sodium channels. However, fetal glomerular number was lower after ethanol exposure (377,585 Ϯ 8,325) than in controls (423,177 Ϯ 17,178, P Ͻ 0.001). The data demonstrate that our regimen of fetal ethanol exposure during the latter half of gestation results in an 11% reduction in nephron endowment without affecting the overall growth of the kidney or fetus or the expression of key genes involved in renal development or function. A reduced nephron endowment of this magnitude could have important implications for the cardiovascular health of offspring during postnatal life. nephron number; kidney; fetus; ethanol exposure; sheep ALCOHOL (ETHANOL) CONSUMPTION during pregnancy remains common in most developed countries, but recommended guidelines on safe levels of alcohol consumption vary significantly (42). Excessive alcohol consumption during pregnancy is known to result in the fetal alcohol syndrome with characteristic craniofacial dysmorphology, growth restriction, and intellectual dysfunction as the principal diagnostic features manifesting after birth (13,30,34,48). Even moderate levels of alcohol exposure are now known to adversely affect learning and behavior in infants and children. While there is ample evidence that prenatal ethanol exposure can affect central nervous system development, few studies have investigated the effects on other critical organs, such as the kidney. Studies of children diagnosed with FAS demonstrate that some have renal malformations (32, 37); their kidneys are often small, misshapen, and freque...

cardiac contractility, we tested the hypothesis that perinatal rises in these catecholamines (and thus sympathoadrenal activation) was blunted with DCC, or ICC with a non-asphyxial cord clamp-to-ventilation interval. Methods: Anaesthetized preterm fetal lambs (n = 14) were instrumented with 1) aortic (AoT) and pulmonary trunk (PT) micromanometers to obtain pressures, and to derive the maximal rate of pressure rise (dP/dt max) as surrogates of LV and RV contractility, and 2) an AoT catheter to obtain samples for blood gas and catecholamine analyses. Fetuses were delivered and mechanically ventilated prior to cord clamping 1.5 min later (DCC, n = 7), or subjected to ICC with ventilation started ~30 sec later (n = 7), with frequent AoT blood sampling performed before and after birth in both groups. Results: Perinatal haemodynamics were comparatively stable in both groups, without surges in heart rate, blood pressures or dP/dt max after birth. With ICC, NA rose 33% with cord clamping (P < 0.001) and 26% with ventilation (P < 0.02). With DCC, NA rose 23% with cord clamping, and Ad 26% with ventilation (P < 0.02). However, in both groups, circulating NA and Ad remained below threshold levels for haemodynamic effects in preterm lambs (Padbury JF et al, Am J Physiol 252:E530-37, 1986). Conclusions: The presence of haemodynamic stability at birth after DCC, or ICC with a non-asphyxial cord clamp-to-ventilation interval, is accompanied by blunted sympathoadrenal activation. Background: The mechanism underlying varying degrees of haemodynamic fluctuations seen after birth following immediate cord clamping (ICC) at delivery is unclear. This study tested the hypothesis that such fluctuations were related to development of asphyxia with longer cord clamp-to-ventilation intervals, resulting in higher perinatal circulating levels of the catecholamines noradrenaline (NA) and adrenaline (Ad), and thus increased heart rate, blood pressures and cardiac contractility after birth. Methods: Anaesthetized preterm fetal lambs were instrumen-ted with 1) aortic (AoT) and pulmonary trunk (PT) microman-ometers to obtain pressures, and the maximal rate of pressure rise (dP/dt max) as surrogates of LV and RV contractility, and 2) an AoT catheter to obtain samples for blood gas and catecholamine analyses. After delivery, ICC was followed by ventilation ~0.5 min (n = 7), 1 min (n = 8), 1.5 min (n = 9) or 2 min later (n = 8), with frequent blood sampling performed before and after ventilation. Results: AoT O 2 content fell rapidly after ICC (P < 0.001), with asphyxia evident by 1 min. NA and Ad levels were progressively higher with longer cord clamp-to-ventilation intervals, with an exponential relation between falling AoT O 2 content and rising catecholamines (R 2 = 0.7). Elevated catecholamine levels fell after ventilation (P < 0.001), with surges after birth in heart rate, AoT and PT pressures, and AoT and PT dP/dt max having a linear relation to log e of these levels (R 2 = 0.41-0.54, all P < 0.001). Conclusions: These results suggest that 1...

Harding R, Black MJ. Alcohol exposure during late gestation adversely affects myocardial development with implications for postnatal cardiac function. Am J Physiol Heart Circ Physiol 300: H645-H651, 2011. First published November 12, 2010 doi:10.1152/ajpheart.00689.2010.-Prenatal exposure to high levels of ethanol is associated with cardiac malformations, but the effects of lower levels of exposure on the heart are unclear. Our aim was to investigate the effects of daily exposure to ethanol during late gestation, when cardiomyocytes are undergoing maturation, on the developing myocardium. Pregnant ewes were infused with either ethanol (0.75 g/kg) or saline for 1 h each day from gestational days 95 to 133 (term ϳ145 days); tissues were collected at 134 days. In sheep, cardiomyocytes mature during late gestation as in humans. Within the left ventricle (LV), cardiomyocyte number was determined using unbiased stereology and cardiomyocyte size and nuclearity determined using confocal microscopy. Collagen deposition was quantified using image analysis. Genes relating to cardiomyocyte proliferation and apoptosis were examined using quantitative real-time PCR. Fetal plasma ethanol concentration reached 0.11 g/dL after EtOH infusions. Ethanol exposure induced significant increases in relative heart weight, relative LV wall volume, and cardiomyocyte cross-sectional area. Ethanol exposure advanced LV maturation in that the proportion of binucleated cardiomyocytes increased by 12%, and the number of mononucleated cardiomyocytes was decreased by a similar amount. Apoptotic gene expression increased in the ethanol-exposed hearts, although there were no significant differences between groups in total cardiomyocyte number or interstitial collagen. Daily exposure to a moderate dose of ethanol in late gestation accelerates the maturation of cardiomyocytes and increases cardiomyocyte and LV tissue volume in the fetal heart. These effects on cardiomyocyte growth may program for long-term cardiac vulnerability.