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Di Paola M, Sierra MN, Fernández N, Ibarra C, Damiano AE. Contribution of aquaporins in the transamniotic water flux. Biochem Biophys Res Commun 2021; 590:63-67. [PMID: 34971959 DOI: 10.1016/j.bbrc.2021.12.097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 12/25/2021] [Indexed: 11/02/2022]
Abstract
We explored the contribution of each aquaporin (AQP) expressed in human amnion in the transcellular water flux across the human amnion. Human amnion was placed between two lucite chambers and net water transport (Jw) was recorded by applying a hydrostatic (7 cm H2O) and an osmotic (40 mOsm PEG 8000) pressure gradients. The hydrostatic (Phydr) and osmotic (POsm) permeabilities were calculated before and after the blocking of AQPs. Phdr showed no significant difference after the blocking of AQPs, while POsm was dramatically reduced. Interestingly, we also found that the blocking of AQP1 produced the highest decrease of POsm (80 ± 1%). Our results strongly suggested that AQP1 seems to contribute more to the maintenance of AF volume homeostasis.
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Affiliation(s)
- Mauricio Di Paola
- Cátedra de Biología Celular y Molecular, Departamento de Ciencias Biológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina; Laboratorio de Biología de la Reproducción, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO)- CONICET- Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Matías N Sierra
- Cátedra de Biología Celular y Molecular, Departamento de Ciencias Biológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Nazarena Fernández
- Cátedra de Biología Celular y Molecular, Departamento de Ciencias Biológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Cristina Ibarra
- Laboratorio de Fisiopatogenia, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO)- CONICET- Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Alicia E Damiano
- Cátedra de Biología Celular y Molecular, Departamento de Ciencias Biológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina; Laboratorio de Biología de la Reproducción, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO)- CONICET- Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.
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Amniotic Aaquaporins (AQP) in Normal and Pathological Pregnancies: Interest in Polyhydramnios. Reprod Sci 2021; 28:2929-2938. [PMID: 34254277 DOI: 10.1007/s43032-021-00677-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 06/18/2021] [Indexed: 10/20/2022]
Abstract
Polyhydramnios is a common feature diagnosed by ultrasound in the second half of pregnancy. Biochemical analysis of amniotic fluid can be useful when suspecting Bartter syndrome or digestive atresia but in most of cases, no etiology of polyhydramnios is found because of the complex regulation of amniotic fluid. Aquaporins (AQP) are transmembrane channel proteins contributing to water transfers. Some of them are expressed in fetal membranes and placenta. Their expression has been shown to be disrupted in some pathological conditions such as maternal diabetes, often associated with polyhydramnios. AQP-1, 3 and 8 levels in amniotic fluid were retrospectively measured in patients suffering from polyhydramnios (n=21) from 23 weeks of gestation (WG). They were compared to the levels observed in control subjects (n=96) and their relationship with maternal factors and neonatal issues was analyzed. AQP-1, 3, 8 levels were physiologically fluctuating, AQP-1 levels always being the lowest and AQP-3 the highest, with a significant decrease at the end of pregnancy. AQPs/AFP ratios increased about 8 folds during pregnancy, their kinetic profiles reflecting physiological dynamic evolution of amniotic fluid volume. In polyhydramnios, AQP-3 level tended to be decreased whereas AQP-8 level was decreased from mid-gestation whatever the etiology of polyhydramnios. No significant relationship was found between AQPs levels and either the fetal prematurity degree or macrosomia. No specific pattern was observed in idiopathic polyhydramnios, limiting the interest of AQPs dosage in amniotic fluid in the management of those complicated pregnancies.
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N-terminal pro-B-type natriuretic peptide in amniotic fluid of fetuses with known or suspected cardiac load. PLoS One 2017; 12:e0177253. [PMID: 28545116 PMCID: PMC5436674 DOI: 10.1371/journal.pone.0177253] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 04/25/2017] [Indexed: 12/14/2022] Open
Abstract
Background Myocardial dysfunction occurs in a variety of fetal disorders. Findings from adult cardiology, where n-terminal pro-B-type natriuretic peptide (nt-proBNP) is an established biomarker of left ventricular dysfunction have been extended to fetal life. Since fetal blood sampling is technically challenging we investigated amniotic fluid nt-proBNP for its suitability to diagnose fetal myocardial dysfunction. Methods Ultrasound, Doppler examination and echocardiography was applied to classify cases and controls. Amniotic fluid nt-proBNP to amniotic fluid total protein ratio was calculated and compared to the gestational age-dependent reference intervals. In a subset of cases, fetal and maternal plasma nt-proBNP levels were determined. Results Specimen from 391 fetuses could be analyzed (171 cases, 220 controls). There was a high correlation between amniotic fluid and fetal blood nt-proBNP levels (r = 0.441 for cases; r = 0.515 for controls), whereas no correlation could be detected between maternal and fetal (blood and amniotic fluid) nt-proBNP concentrations. Specificity and positive likelihood ratio of amniotic fluid nt-proBNP to amniotic fluid total protein ratio were high (0.97 and 4.3, respectively). Conclusion Amniotic fluid nt-proBNP measurement allows diagnostic confirmation of fetal myocardial dysfunction. It may serve as a useful adjunct in addition and correlation to existing tests of myocardial function, particularly in the context of invasive fetal therapy, where access to the amniotic cavity is part of the procedure.
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Cheung CY. Vascular Endothelial Growth Factor Activation of Intramembranous Absorption: A Critical Pathway for Amniotic Fluid Volume Regulation. ACTA ACUST UNITED AC 2016; 11:63-74. [PMID: 14980307 DOI: 10.1016/j.jsgi.2003.09.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE The purpose of this review is to propose a critical role for vascular endothelial growth factor (VEGF) in mediating the transfer of amniotic fluid from the amniotic compartment through the fetal membranes and fetal surface of the placenta into fetal blood. METHODS Experimental findings in humans and animal models on the action of VEGF in mediating fluid transfer are reviewed and interpreted in order to postulate a proposed mechanism for VEGF regulation of amniotic fluid absorption through the fetal membranes and placenta. RESULTS Recent scientific advances suggest that up-regulation of VEGF gene expression in the amnion and chorion is associated with increased transfer of amniotic fluid into fetal blood. The possible mechanisms of action for VEGF appear to involve regulation of intramembranous blood vessel proliferation and membrane transport via passive permeation as well as nonpassive transcytotic vesicular movement of fluid. CONCLUSION Currently evolving concepts suggest that amniotic fluid volume is regulated through modulation of the rate of intramembranous absorption of amniotic fluid by both passive and nonpassive mechanisms. The permeability factor VEGF appears to be a critical regulator of amniotic fluid transport in the fetal membranes.
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Affiliation(s)
- Cecilia Y Cheung
- Division of Perinatal Medicine, Department of Reproductive Medicine, University of California at San Diego, La Jolla, California 92093-0802, USA.
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Bagci S, Brosens E, Tibboel D, De Klein A, Ijsselstijn H, Wijers CHW, Roeleveld N, de Blaauw I, Broens PM, van Rooij IALM, Hölscher A, Boemers TM, Pauly M, Münsterer OJ, Schmiedeke E, Schäfer M, Ure BE, Lacher M, Choinitzki V, Schumacher J, Zwink N, Jenetzky E, Katzer D, Arand J, Bartmann P, Reutter HM. More than fetal urine: enteral uptake of amniotic fluid as a major predictor for fetal growth during late gestation. Eur J Pediatr 2016; 175:825-31. [PMID: 26979529 DOI: 10.1007/s00431-016-2713-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 02/25/2016] [Accepted: 03/03/2016] [Indexed: 11/26/2022]
Abstract
UNLABELLED The purpose of our study was to investigate the importance of amniotic fluid (AF) for fetal growth during late gestation using esophageal atresia (EA) patients as a model. In this retrospective cohort study, we compared the z-scores adapted for birth weights (BW z-scores) for each of 517 European newborns with congenital pre-gastric intestinal atresia, i.e., EA, to a European reference population. To account for the influence of the intestinal atresia on fetal growth per se, we compared adapted birth weights for each of 504 European newborns with post colonic intestinal atresia (anorectal malformation (ARM) with atresia of the anus) to the same European reference population. Analysis of the complete cohort showed (i) a significantly higher rate of small for gestational age newborns among EA compared to ARM newborns (p < 0.001) and (ii) significantly lower BW z-scores among EA compared to ARM newborns (p < 0.001). BW z-scores of EA newborns were significantly lower in term compared to preterm newborns with an inverse correlation with gestational age (GA) (Spearman correlation coefficient, r = -0.185, p < 0.001). CONCLUSIONS Enteral uptake of AF seems to play a pivotal role in fetal growth during late gestation. WHAT IS KNOWN • Peak velocity of fetal weight gain occurs at 33 weeks of gestation and continues until birth. During this period, fetal growth is mainly characterized by cellular hypertrophy. • Amniotic fluid (AF) comprises large amounts of hormones and growth regulators. What is New: • A significantly higher rate of small for gestational age and lower birth weights and z-scores are observed among newborn infants with congenital pre-gastric intestinal atresia. • These findings suggest that enteral uptake of AF is a major predictor for fetal growth during late gestation.
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Affiliation(s)
- Soyhan Bagci
- Department of Neonatology and Pediatric Intensive Care, Children's Hospital, University of Bonn, Adenauerallee 119, 53113, Bonn, Germany.
| | - Erwin Brosens
- Department of Clinical Genetics, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Dick Tibboel
- Department of Pediatric Surgery and Intensive Care, Erasmus Medical Centre-Sophia Children's Hospital, Rotterdam, The Netherlands
| | - Annelies De Klein
- Department of Clinical Genetics, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Hanneke Ijsselstijn
- Department of Pediatric Surgery and Intensive Care, Erasmus Medical Centre-Sophia Children's Hospital, Rotterdam, The Netherlands
| | - Charlotte H W Wijers
- Department for Health Evidence, Radboud Institute for Health Sciences, Radboudumc, Nijmegen, The Netherlands
| | - Nel Roeleveld
- Department for Health Evidence, Radboud Institute for Health Sciences, Radboudumc, Nijmegen, The Netherlands
| | - Ivo de Blaauw
- Department of Surgery-Pediatric Surgery, Radboudumc Amalia Children's Hospital, Nijmegen, The Netherlands
| | - Paul M Broens
- Department of Surgery, Anorectal Physiology Laboratory, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- Department of Surgery, Division of Pediatric Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Iris A L M van Rooij
- Department for Health Evidence, Radboud Institute for Health Sciences, Radboudumc, Nijmegen, The Netherlands
| | - Alice Hölscher
- Department of Pediatric Surgery and Urology, University Hospital Cologne, Cologne, Germany
| | - Thomas M Boemers
- Department of Pediatric Surgery and Urology, University Hospital Cologne, Cologne, Germany
| | - Marcus Pauly
- Department of Pediatric Surgery, Asklepios Children's Hospital St. Augustin, St. Augustin, Germany
| | - Oliver J Münsterer
- Department of Pediatric Surgery, University Medicine of Mainz, Mainz, Germany
| | - Eberhard Schmiedeke
- Department of Pediatric Surgery and Urology, Center for Child and Youth Health, Klinikum Bremen-Mitte, Bremen, Germany
| | - Mattias Schäfer
- Department of Pediatric Surgery and Urology, Cnopf'sche Kinderklinik, Nürnberg, Germany
| | - Benno E Ure
- Center of Pediatric Surgery Hannover, Hannover Medical School and Bult Children's Hospital, Hannover, Germany
| | - Martin Lacher
- Center of Pediatric Surgery Hannover, Hannover Medical School and Bult Children's Hospital, Hannover, Germany
| | - Vera Choinitzki
- Institute of Human Genetics, University of Bonn, Bonn, Germany
| | | | - Nadine Zwink
- Division of Clinical Epidemiology and Aging Research, German Cancer Research Center, Heidelberg, Germany
| | - Ekkehart Jenetzky
- Division of Clinical Epidemiology and Aging Research, German Cancer Research Center, Heidelberg, Germany
- Department of Child and Adolescent Psychiatry and Psychotherapy, Johannes-Gutenberg University, Mainz, Germany
| | - David Katzer
- Department of Neonatology and Pediatric Intensive Care, Children's Hospital, University of Bonn, Adenauerallee 119, 53113, Bonn, Germany
| | - Joerg Arand
- Department of Neonatology, University Children's Hospital of Tübingen, University of Tübingen, Tübingen, Germany
| | - Peter Bartmann
- Department of Neonatology and Pediatric Intensive Care, Children's Hospital, University of Bonn, Adenauerallee 119, 53113, Bonn, Germany
| | - Heiko M Reutter
- Department of Neonatology and Pediatric Intensive Care, Children's Hospital, University of Bonn, Adenauerallee 119, 53113, Bonn, Germany
- Institute of Human Genetics, University of Bonn, Bonn, Germany
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Hiccups and amniotic fluid regulation in early pregnancy. Med Hypotheses 2015; 84:448-50. [PMID: 25754848 DOI: 10.1016/j.mehy.2015.01.040] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 01/27/2015] [Indexed: 11/22/2022]
Abstract
Hiccups are an unexplained phenomenon and a subject of medical curiosity. They arise through a reflex arc with central control at the level of the medulla, and their primary physiological effect is the generation of negative intra-thoracic pressure. This paper presents the hypothesis that hiccups serve a purpose during the first half of gestation, when they are most prevalent; namely, that they promote amniotic fluid influx to the primitive gut, allowing fluid to be transferred to the foetal and then maternal vasculature. Furthermore, hiccups could be provoked by increasing amniotic fluid volume and pressure, and act in a regulatory capacity. This hypothesis could be tested by studying foetal movements in the first half of gestation, and assessing whether there is correlation with amniotic fluid flux in the developing gut. Ascertaining whether hiccups increase in frequency with increasing amniotic fluid volume would provide evidence for or against a regulatory function.
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Merz WM, Leufgen C, Fimmers R, Stoffel-Wagner B, Gembruch U. Reference intervals for N-terminal pro-B-type natriuretic peptide in amniotic fluid between 10 and 34 weeks of gestation. PLoS One 2014; 9:e114416. [PMID: 25490554 PMCID: PMC4260852 DOI: 10.1371/journal.pone.0114416] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 11/10/2014] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND In adult and pediatric cardiology, n-terminal pro-B-type natriuretic peptide (nt-proBNP) serves as biomarker in the diagnosis and management of cardiovascular dysfunction. Elevated levels of circulating nt-proBNP are present in fetal conditions associated with myocardial pressure or volume load. Compared to fetal blood sampling, amniocentesis is technically easier and can be performed from early pregnancy onwards. We aimed to investigate amniotic fluid (AF) nt-proBNP concentrations in normal pregnancies between 10 and 34 weeks of gestation. METHODS Nt-proBNP and total protein (TP) was measured in AF by chemiluminescence assay (photometry, respectively). To adjust for a potential dilutional effect, the AF-nt-proBNP/AF-TP ratio was analyzed. Reference intervals were constructed by regression modeling across gestational age. RESULTS 132 samples were analyzed. A negative correlation between AF-nt-proBNP/AF-TP ratio and gestational age was observed. Curves for the mean and the 5% and 95% reference interval between 10 and 34 weeks of gestation were established. CONCLUSION In normal pregnancy, nt-proBNP is present in AF and decreases during gestation. Our data provide the basis for research on AF-nt-proBNP as biomarker in fetal medicine.
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Affiliation(s)
- Waltraut M. Merz
- Department of Obstetrics and Prenatal Medicine, University Bonn Medical School, Bonn, Germany
| | - Christina Leufgen
- Department of Obstetrics and Prenatal Medicine, University Bonn Medical School, Bonn, Germany
| | - Rolf Fimmers
- Institute for Medical Biometry, Informatics and Epidemiology, University Bonn Medical School, Bonn, Germany
| | - Birgit Stoffel-Wagner
- Institute for Clinical Chemistry and Pharmacology, University Bonn Medical School, Bonn, Germany
| | - Ulrich Gembruch
- Department of Obstetrics and Prenatal Medicine, University Bonn Medical School, Bonn, Germany
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Brace RA, Anderson DF, Cheung CY. Regulation of amniotic fluid volume: mathematical model based on intramembranous transport mechanisms. Am J Physiol Regul Integr Comp Physiol 2014; 307:R1260-73. [PMID: 25186112 PMCID: PMC4233290 DOI: 10.1152/ajpregu.00283.2014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 08/28/2014] [Indexed: 11/22/2022]
Abstract
Experimentation in late-gestation fetal sheep has suggested that regulation of amniotic fluid (AF) volume occurs primarily by modulating the rate of intramembranous transport of water and solutes across the amnion into underlying fetal blood vessels. In order to gain insight into intramembranous transport mechanisms, we developed a computer model that allows simulation of experimentally measured changes in AF volume and composition over time. The model included fetal urine excretion and lung liquid secretion as inflows into the amniotic compartment plus fetal swallowing and intramembranous absorption as outflows. By using experimental flows and solute concentrations for urine, lung liquid, and swallowed fluid in combination with the passive and active transport mechanisms of the intramembranous pathway, we simulated AF responses to basal conditions, intra-amniotic fluid infusions, fetal intravascular infusions, urine replacement, and tracheoesophageal occlusion. The experimental data are consistent with four intramembranous transport mechanisms acting in concert: 1) an active unidirectional bulk transport of AF with all dissolved solutes out of AF into fetal blood presumably by vesicles; 2) passive bidirectional diffusion of solutes, such as sodium and chloride, between fetal blood and AF; 3) passive bidirectional water movement between AF and fetal blood; and 4) unidirectional transport of lactate into the AF. Further, only unidirectional bulk transport is dynamically regulated. The simulations also identified areas for future study: 1) identifying intramembranous stimulators and inhibitors, 2) determining the semipermeability characteristics of the intramembranous pathway, and 3) characterizing the vesicles that are the primary mediators of intramembranous transport.
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Affiliation(s)
- Robert A Brace
- Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology Oregon Health and Science University, Portland, Oregon; and Center for Developmental Health Oregon Health and Science University, Portland, Oregon
| | - Debra F Anderson
- Center for Developmental Health Oregon Health and Science University, Portland, Oregon
| | - Cecilia Y Cheung
- Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology Oregon Health and Science University, Portland, Oregon; and Center for Developmental Health Oregon Health and Science University, Portland, Oregon
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Brace RA, Anderson DF, Cheung CY. Fetal swallowing as a protective mechanism against oligohydramnios and polyhydramnios in late gestation sheep. Reprod Sci 2012; 20:326-30. [PMID: 22872543 DOI: 10.1177/1933719112453510] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
UNLABELLED Our objectives were to (1) quantify the relationship between daily swallowed volume and amniotic fluid volume (AF volume) in late gestation ovine fetuses and (2) use the resulting regression equation to explore the role of swallowing in regulating AF volume. Daily swallowed volume ranged from 36 to 1963 mL/d while experimental AF volume ranged from 160 to 6150 mL (n = 115). Swallowed volume was near zero when AF volume was far below normal, a maximum of 635 ± 41 (standard error) mL/d when AF volume was 1682 ± 31 mL and did not increase further with higher AF volumes. Computer simulations predicted that fetal swallowing would (1) return AF volume to normal in 5 to 6 days following an acute volume change in the absence of changes in other amniotic inflows or outflows and (2) stabilize AF volume in 4 to 8 days following sustained alterations in amniotic inflows or outflows other than swallowing. CONCLUSIONS The volume of AF swallowed each day by the fetus is a strong function of AF volume and reaches a maximum when mild polyhydramnios develops. With deviations in AF volume from normal, changes in fetal swallowing protect against oligohydramnios and polyhydramnios because the changes in swallowing over time reduce the extent of the AF volume change. However, with experimental changes in AF volume stabilizing in 1 to 2 days, it appears that swallowing is not the major regulator of AF volume.
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Affiliation(s)
- Robert A Brace
- Department of Obstetrics and Gynecology, Oregon Health and Science University, Portland, OR 97239, USA.
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Magann EF, Sandlin AT, Ounpraseuth ST. Amniotic fluid and the clinical relevance of the sonographically estimated amniotic fluid volume: oligohydramnios. JOURNAL OF ULTRASOUND IN MEDICINE : OFFICIAL JOURNAL OF THE AMERICAN INSTITUTE OF ULTRASOUND IN MEDICINE 2011; 30:1573-1585. [PMID: 22039031 DOI: 10.7863/jum.2011.30.11.1573] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The amniotic fluid volume (AFV) is regulated by several systems, including the in-tramembranous pathway, fetal production (fetal urine and lung fluid) and uptake (fetal swallowing), and the balance of fluid movement via osmotic gradients. The normal AFV across gestation has not been clearly defined; consequently, abnormal volumes are also poorly defined. Actual AFVs can be measured by dye dilution techniques and directly measured at cesarean delivery; however, these techniques are time-consuming, are invasive, and require laboratory support, and direct measurement can only be done at cesarean delivery. As a result of these limitations, the AFV is estimated by the amniotic fluid index (AFI), the single deepest pocket, and subjective assessment of the AFV. Unfortunately, sonographic estimates of the AFV correlate poorly with dye-determined or directly measured amniotic fluid. The recent use of color Doppler sonography has not improved the diagnostic accuracy of sonographic estimates of the AFV but instead has led to overdiagnosis of oligohydramnios. The relationship between the fixed cutoffs of an AFI of 5 cm or less and a single deepest pocket of 2 cm or less for identifying adverse pregnancy outcomes is uncertain. The use of the single deepest pocket compared to the AFI to identify oligohydramnios in at-risk pregnancies seems to be a better choice because the use of the AFI leads to an increase in the diagnosis of oligohydramnios, resulting in more labor inductions and cesarean deliveries without any improvement in peripartum outcomes.
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Affiliation(s)
- Everett F Magann
- Department of Obstetrics and Gynecology, University of Arkansas for the Medical Sciences, Little Rock, AR 72205 USA.
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Kobayashi K, Miwa H, Yasui M. Progesterone maintains amniotic tight junctions during midpregnancy in mice. Mol Cell Endocrinol 2011; 337:36-42. [PMID: 21291956 DOI: 10.1016/j.mce.2011.01.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Revised: 01/25/2011] [Accepted: 01/25/2011] [Indexed: 01/01/2023]
Abstract
The amniotic epithelium is in direct contact with the amniotic fluid and restricts fluid flux via the paracellular pathway by means of tight junctions (TJs). Several factors affect TJs to modulate the paracellular flux. Progesterone contributes to the antenatal formation and disappearance of TJs in uterine and mammary epithelial tissues. In this study, we investigated whether progesterone positively or negatively influences amniotic TJs. The administration of RU-486, a progesterone receptor (PR) antagonist, into pregnant mice adversely affects the localization and expression of claudin-3 and claudin-4 in the amniotic epithelium. RU-486 administration also increased the permeability of the amniotic membrane. In organ-cultured amniotic membranes, progesterone induced increases in claudin-3 and claudin-4 expression in a dose-dependent manner but did not influence their localization. PRs were also present in the amniotic epithelium during midpregnancy but they disappeared during late pregnancy. These results indicate that the progesterone/PR pathway maintains TJs in the amniotic epithelium during midpregnancy.
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Affiliation(s)
- Ken Kobayashi
- Department of Pharmacology, School of Medicine, Keio University, Tokyo, Japan.
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Kobayashi K, Yasui M. Cellular and subcellular localization of aquaporins 1, 3, 8, and 9 in amniotic membranes during pregnancy in mice. Cell Tissue Res 2010; 342:307-16. [DOI: 10.1007/s00441-010-1065-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Accepted: 09/17/2010] [Indexed: 12/12/2022]
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Kobayashi K, Kadohira I, Tanaka M, Yoshimura Y, Ikeda K, Yasui M. Expression and distribution of tight junction proteins in human amnion during late pregnancy. Placenta 2009; 31:158-62. [PMID: 20018370 DOI: 10.1016/j.placenta.2009.11.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2009] [Revised: 11/24/2009] [Accepted: 11/24/2009] [Indexed: 10/20/2022]
Abstract
Amnion is the innermost layer of the fetal membrane and has been suggested to regulate the volume of amniotic fluid via the amniotic epithelium. The transepithelial pathway is generally restricted by tight junctions (TJs). Thus far, human amniotic TJs have not been identified. In this study, we determined whether the human amniotic epithelium contains TJs. Reverse transcription polymerase chain reaction (RT-PCR) and western blotting analyses showed that the human amniotic epithelium has TJ components, such as occludin, ZO-1, and at least 2 types of claudins, i.e., claudin-4 and claudin-7. The TJ components were found to localize in the lateral membranes and cytoplasm at 35 weeks of gestation; these components disappeared from the lateral membrane at 37 weeks of gestation. Organ culturing of the amnion at 37 weeks gestation induced the relocalization of the TJ proteins from the cytoplasm to the lateral membranes. Furthermore, in cultured amniotic epithelial cells, dexamethasone induced the downregulation of the protein expression of TJs. These findings suggest that the human amniotic epithelium has TJs that disrupt during late pregnancy. The disruption may be induced by several factors such as glucocorticoids present in the amniotic fluid during late pregnancy.
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Affiliation(s)
- K Kobayashi
- Department of Pharmacology, School of Medicine, Keio University, Tokyo, Japan
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Qi H, Li L, Zong W, Hyer BJ, Huang J. Expression of aquaporin 8 is diversely regulated by osmotic stress in amnion epithelial cells. J Obstet Gynaecol Res 2009; 35:1019-25. [DOI: 10.1111/j.1447-0756.2009.01061.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Zhu X, Jiang S, Zhu X, Zou S, Wang Y, Hu Y. Expression of Aquaporin 1 and Aquaporin 3 in Fetal Membranes and Placenta in Human Term Pregnancies with Oligohydramnios. Placenta 2009; 30:670-6. [DOI: 10.1016/j.placenta.2009.05.010] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Revised: 05/20/2009] [Accepted: 05/23/2009] [Indexed: 11/30/2022]
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16
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Robertson P, Faber JJ, Brace RA, Louey S, Hohimer AR, Davis LE, Anderson DF. Responses of amniotic fluid volume and its four major flows to lung liquid diversion and amniotic infusion in the ovine fetus. Reprod Sci 2009; 16:88-93. [PMID: 19144891 DOI: 10.1177/1933719108324888] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We designed experiments to allow direct measurement of amniotic fluid volume and continuous measurement of lung liquid production, swallowing, and urine production in fetal sheep. From these values, the rate of intramembranous absorption was calculated. Using this experimental design, the contribution of lung liquid to the control of amniotic fluid volume was examined. Fetuses were assigned to 1 of 4 protocols, each protocol lasting 3 days: control, isovolemic replacement of lung liquid, supplementation of amniotic fluid inflow by 4 L/day, and supplementation of amniotic inflow during isovolemic replacement of lung liquid. We found no effect of lung liquid replacement on any of the known flows into and out of the amniotic fluid. Although intramembranous absorption increased greatly during supplementation, the amniochorionic function curves were not altered by isovolemic lung liquid replacement. We conclude that lung liquid does not appear to contain a significant regulatory substance for amniotic fluid volume control.
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Affiliation(s)
- Patricia Robertson
- Department of Obstetrics and Gynecology, Oregon Health and Science University, Portland, Oregon 97239, USA.
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17
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Amniotic fluid volume responses to esophageal ligation in fetal sheep: contribution of lung liquid. Am J Obstet Gynecol 2009; 200:313.e1-6. [PMID: 19114273 DOI: 10.1016/j.ajog.2008.10.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 08/27/2008] [Accepted: 10/07/2008] [Indexed: 11/20/2022]
Abstract
OBJECTIVE The objective of the study was to determine the amniotic fluid volume (AFV) response to fetal esophageal ligation with and without fetal lung liquid entering the amniotic sac. STUDY DESIGN AFV was measured in 3 groups of late-gestation ovine fetuses: time controls, tracheoesophageal shunted, and esophageal ligated. RESULTS One day after surgery, AFV was similar in all groups, averaging 1064 +/- 66 mL. On postsurgical day 9, AFV was unchanged in control fetuses, increased to 3025 +/- 294 mL in fetuses with esophageal ligation and lung liquid shunted into the fetal stomach, and to 3437 +/- 430 mL in fetuses with esophageal ligation and no shunting. CONCLUSION AFV expanded gradually following esophageal ligation to the highest volume thus far reported in noninfused ovine fetuses. Lung liquid entry into the amniotic sac altered neither the time course nor the extent of the AFV increase following esophageal ligation.
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Shi L, Mao C, Zeng F, Zhu L, Xu Z. Central cholinergic mechanisms mediate swallowing, renal excretion, and c-fos expression in the ovine fetus near term. Am J Physiol Regul Integr Comp Physiol 2008; 296:R318-25. [PMID: 19005017 DOI: 10.1152/ajpregu.90632.2008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fetal swallowing and renal metabolism contribute importantly to amniotic and body fluid homeostasis. To determine central cholinergic modulation of swallowing activity and renal excretion associated with neural activity, we examined the effects of intracerebroventricular injection of carbachol, a cholinergic agonist, in ovine fetuses at 0.9 gestation. Fetuses were chronically prepared with thyrohyoid, nuchal and thoracic esophagus, and diaphragm electromyogram electrodes, as well as lateral ventricle and vascular catheters. Electrodes were also implanted on the parietal dura for determination of fetal electrocorticogram (ECoG). After 5 days of recovery, fetal swallowing, ECoG, and urine output were monitored during basal period and the experimental period following intracerebroventricular injection of 0.9% NaCl as the control (n = 5) or carbachol (3 microg/kg, n = 5). Central carbachol did not significantly change fetal low voltage (LV) and high voltage (HV) ECoG temporal distributions. However, swallowing activity during LV ECoG was elevated significantly after intracerebroventricular carbachol. Associated with the swallowing activation, c-fos immunoreactivity in the putative dipsogenic center, subfornical organ, was enhanced significantly. The fetal urine flow rate and renal Na+, K+, and Cl(-) excretion were markedly increased following intracerebroventricular carbachol and sustained at the high level for at least 2 h. The results indicate that the central cholinergic mechanism is established and functional in regulation of fetal behavior and renal excretion at least at 0.9 gestation, which plays an important role in maintenance of fetal body fluid homeostasis.
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Affiliation(s)
- Lijun Shi
- Department of Human Sport Science, Beijing Sport University, Beijing, China
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19
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Cheung CY, Brace RA. Hypoxia modulation of caveolin-1 and vascular endothelial growth factor in ovine fetal membranes. Reprod Sci 2008; 15:469-76. [PMID: 18579855 DOI: 10.1177/1933719107312561] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
During normal pregnancy, amniotic fluid is absorbed from the amniotic compartment into fetal blood through the intramembranous blood vessels in the fetal membranes. It has been hypothesized that this transport process is mediated by transcytosis of caveolae-like vesicles. Because fetal hypoxia increases intramembranous absorption, the authors explore the effects of hypoxia on the gene expression of caveolin-1, a structural protein of caveolae, in ovine fetal membranes and cultured amnion cells. Near-term ovine fetuses were rendered hypoxic for 4 days. Caveolin-1 mRNA and protein levels were significantly reduced in the amnion and chorion but not in the placenta. In cultured ovine amnion cells incubated in 2% oxygen for 24 hours, hypoxia did not significantly alter caveolin-1 mRNA or protein expression. Vascular endothelial growth factor mRNA levels were increased in response to hypoxia in the fetal membranes as well as in cultured amnion cells. The results indicate that hypoxia does not augment but instead down-regulates or has no effect on caveolin-1 gene expression in the amnion and chorion, suggesting that caveolin-1 may play a role as a negative regulator of amnion transport function under hypoxic conditions.
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Affiliation(s)
- Cecilia Y Cheung
- Department of Obstetrics and Gynecology, Oregon Health and Science University, Portland, Oregon 97239, USA.
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20
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Amidi F, Beall M, Ross MG. Cyclic adenosine monophosphate regulation of aquaporin gene expression in human amnion epithelia. Reprod Sci 2007; 14:234-40. [PMID: 17636236 DOI: 10.1177/1933719107300970] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cell membrane aquaporins (AQPs) may con t r i b u t e importantly to the regulation of intramembranous absorption of amniotic fluid. Recently, the authors demonstrated that human amnion AQP3 expression is upregulated by second-messenger cyclic adenosine monophosphate (cAMP). The present study was undertaken to determine the cAMP regulation of other AQP types, specifically AQP1, 8, and 9, in human amnion epithelia in vitro. Human amnion epithelial cell cultures were prepared from amnion of normal-term pregnancy. To investigate the effect of cAMP on AQP expression, primary human amnion cell cultures were incubated for 2, 10, and 20 hours with culture medium containing either 50 microM forskolin, an adenylate cyclase activator that stimulates cellular production of cAMP, or 100 microM SP-cAMP, a cAMP agonist that stimulates protein kinase A. Total RNA was isolated from the cultured cells, and semiquantitative real-time reverse transcription polymerase chain reaction was carried out to determine the relative level of AQPs mRNA expression. In primary amnion epithelial cell culture, AQP1 mRNA expression increased significantly at 10 hours (0.219 +/- 0.006 to 0.314 +/- 0.008, P < .05) and remained elevated for 20 hours (0.223 +/- 0.004 to 0.323 +/- 0.012, P < .05) following forskolin treatment. AQP8 mRNA expression increased significantly at 2 hours (0.069 +/- 0.003 to 0.086 +/- 0.012, P < .05) and remained upregulated for 20 hours following forskolin treatment. Forskolin stimulation of AQP9 mRNA expression was evidenced by 10 hours (0.098 +/- 0.005 to 0.115 +/- 0.006, P < .05) and maintained for 20 hours. In contrast to forskolin, SP-cAMP incubation resulted in no change in AQP1, 8, or 9 mRNA expression. Human amnion epithelial cell AQP1, 8, and 9 mRNA expression is upregulated by cAMP as their expression is simulated by forskolin. Lack of effect of SP-cAMP, the protein kinase A activator, on AQP1, 8, and 9 mRNA expression suggests that cAMP upregulates human amnion AQP1, 8, and 9 mRNA expression via the protein kinase A independent pathway.
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Abstract
Water arrives in the mammalian gestation from the maternal circulation across the placenta. It then circulates between the fetal water compartments, including the fetal body compartments, the placenta and the amniotic fluid. Amniotic fluid is created by the flow of fluid from the fetal lung and bladder. A major pathway for amniotic fluid resorption is fetal swallowing; however, in many cases the amounts of fluid produced and absorbed do not balance. A second resorption pathway, the intramembranous pathway (across the amnion to the fetal circulation), has been proposed to explain the maintenance of normal amniotic fluid volume. Amniotic fluid volume is thus a function both of the amount of water transferred to the gestation across the placental membrane, and the flux of water across the amnion. Water flux across biologic membranes may be driven by osmotic or hydrostatic forces; existing data suggest that intramembranous flow in humans is driven by the osmotic difference between the amniotic fluid and the fetal serum. The driving force for placental flow is more controversial, and both forces may be in effect. The mechanism(s) responsible for regulating water flow to and from the amniotic fluid is unknown. In other parts of the body, notably the kidney, water flux is regulated by the expression of aquaporin water channels on the cell membrane. We hypothesize that aquaporins have a role in regulating water flux across both the amnion and the placenta, and present evidence in support of this theory. Current knowledge of gestational water flow is sufficient to allow prediction of fetal outcome when water flow is abnormal, as in twin-twin transfusion syndrome. Further insight into these mechanisms may allow novel treatments for amniotic fluid volume abnormalities with resultant improvement in clinical outcome.
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Affiliation(s)
- M H Beall
- Department of Obstetrics and Gynecology, Harbor-UCLA Medical Center, 1000 W. Carson Street, Box 3, Torrance, CA 90502, USA.
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Beall MH, van den Wijngaard JPHM, van Gemert MJC, Ross MG. Amniotic fluid water dynamics. Placenta 2007; 28:816-23. [PMID: 17254633 DOI: 10.1016/j.placenta.2006.11.009] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Revised: 11/28/2006] [Accepted: 11/30/2006] [Indexed: 11/27/2022]
Abstract
Water arrives in the mammalian gestation from the maternal circulation across the placenta. It then circulates between the fetal water compartments, including the fetal body compartments, the placenta and the amniotic fluid. Amniotic fluid is created by the flow of fluid from the fetal lung and bladder. A major pathway for amniotic fluid resorption is fetal swallowing; however in many cases the amounts of fluid produced and absorbed do not balance. A second resorption pathway, the intramembranous pathway (across the amnion to the fetal circulation), has been proposed to explain the maintenance of normal amniotic fluid volume. Amniotic fluid volume is thus a function both of the amount of water transferred to the gestation across the placental membrane, and the flux of water across the amnion. Membrane water flux is a function of the water permeability of the membrane; available data suggests that the amnion is the structure limiting intramembranous water flow. In the placenta, the syncytiotrophoblast is likely to be responsible for limiting water flow across the placenta. In human tissues, placental trophoblast membrane permeability increases with gestational age, suggesting a mechanism for the increased water flow necessary in late gestation. Membrane water flow can be driven by both hydrostatic and osmotic forces. Changes in both osmotic/oncotic and hydrostatic forces in the placenta my alter maternal-fetal water flow. A normal amniotic fluid volume is critical for normal fetal growth and development. The study of amniotic fluid volume regulation may yield important insights into the mechanisms used by the fetus to maintain water homeostasis. Knowledge of these mechanisms may allow novel treatments for amniotic fluid volume abnormalities with resultant improvement in clinical outcome.
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Affiliation(s)
- M H Beall
- Department of Obstetrics and Gynecology, Harbor-UCLA Medical Center, 1000 W. Carson St., Box 3, Torrance, CA 90502, USA.
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Shioji M, Fukuda H, Kanzaki T, Wasada K, Kanagawa T, Shimoya K, Mu J, Sugimoto Y, Murata Y. Reduction of aquaporin-8 on fetal membranes under oligohydramnios in mice lacking prostaglandin F2α receptor. J Obstet Gynaecol Res 2006; 32:373-8. [PMID: 16882262 DOI: 10.1111/j.1447-0756.2006.00425.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIM To investigate the association between aquaporin-8 (AQP-8: a water channel protein) expression in fetal membranes and oligohydramnios during near-term and postdate pregnancy, we set up an oligohydramnios model using prostaglandin F2 alpha receptor (FP)-deficient mice. METHODS Pregnant FP-deficient mice from 14 to 21 gestational days (GD) were killed to measure the amniotic fluid volume (AFV), and fetal membranes were collected for the analysis of aquaporin-8 expression. RESULTS The AFV was highest at 14 GD, and was significantly decreased to 28% and 0% at 20 GD and 21 GD, respectively, compared with the volume at 14 GD. Immunohistochemistry and immunoblot analysis showed that aquaporin-8 was expressed in the basal component of fetal membranes, and that the protein level was significantly decreased to 60% at 20 GD compared with that at 14 GD. CONCLUSIONS We demonstrated that AQP-8 expression in the fetal membrane was decreased at post term in FP-deficient mice. Our findings suggest that aquaporin-8 in fetal membranes may be involved in the regulation of AFV, especially when oligohydramnios occurs.
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Affiliation(s)
- Mitsunori Shioji
- Department of Obstetrics and Gynecology, Osaka University, Graduate School of Medicine, Osaka, Japan
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Komatsu A, Kozuma S, Hyodo H, Horikoshi T, Sakamaki K, Kikuchi A, Kamei Y, Fujii T, Taketani Y. Changes in umbilical arterial blood flow by an intraamniotic distilled water infusion. ACTA ACUST UNITED AC 2006; 13:166-73. [PMID: 16638586 DOI: 10.1016/j.jsgi.2006.01.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2005] [Indexed: 10/24/2022]
Abstract
OBJECTIVES The purpose is to investigate how umbilical arterial blood flow changes by an intraamniotic distilled water infusion and to determine whether the changes in umbilical circulation have any relationship with fetal cardiovascular status and osmolality in amniotic fluid and fetal plasma. METHODS Eleven chronically catheterized pregnant sheep were used in this study. After a 1-hour control period, 1.5 L of warmed sterile distilled water was injected over 10 minutes into the amniotic cavity. Fetal heart rate and carotid arterial pressure, blood flow of the umbilical and fetal carotid arteries were continuously measured. Fetal arterial blood sampled twice during the control period and then at 30, 60, 90, 120, 180, 240, 300, and 360 minutes after the start of the infusion, was analyzed for blood gases, pH, plasma electrolytes, and osmolality. RESULTS Data obtained from seven sheep with normoxemic fetuses were studied statistically. Umbilical arterial blood flow decreased significantly from 229.5 +/- 3.83 mL/min in the control to 167.4 +/- 11.1 mL/min at 30 minutes after water infusion (P < .001). Umbilical arterial vascular resistance increased rapidly and reached its peak at approximately 60 minutes after infusion and then showed a gradual recovery to the control level (P < .001). Amniotic fluid osmolality had a high degree of correlation with umbilical arterial blood flow and vascular resistance, while fetal arterial blood pressure and heart rate had only little correlation with umbilical blood flow. CONCLUSION A distilled water infusion into the amniotic cavity in near-term pregnant sheep led to an acute drop in umbilical arterial blood flow. The changes in umbilical flow were closely correlated with those in amniotic fluid osmolality. Hemolysis in the capillary networks in the fetal membranes seems to be one of the main causes of umbilical vasoconstriction. It is speculated that the fetal membranes, including capillary networks, intramembranous pathway, and amnion epithelial cells, sense the changes in amniotic fluid osmolality, which leads to a fetal adaptation to the hypotonic environment.
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Affiliation(s)
- Atsushi Komatsu
- Department of Obstetrics and Gynecology, University of Tokyo, Tokyo, Japan.
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25
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Cheung CY, Brace RA. Amniotic fluid volume and composition in mouse pregnancy. ACTA ACUST UNITED AC 2006; 12:558-62. [PMID: 16325744 DOI: 10.1016/j.jsgi.2005.08.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/05/2005] [Indexed: 11/20/2022]
Abstract
OBJECTIVE The current study was undertaken to determine simultaneous changes in amniotic fluid (AF) volume and composition across gestation in the pregnant mouse. METHODS Young adult mice (6 to 7 weeks old) of the CB6F1 strain were mated overnight. AF was collected on consecutive days from embryonic days 9.5 through 18.5 for measurements of volume and composition. Statistical analysis included one-factor analysis of variance (ANOVA). RESULTS AF volume increased from 18 +/- 4 (SE) microL on day 9.5 to a maximum of 147 +/- 4 microL on days 15.5 to 16.5 and decreased sharply to 17 +/- 3 microL on day 18.5. AF osmolality was unchanged except for a rise prior to delivery on day 19.5 to 20.5. AF sodium, calcium, and glucose concentrations increased and subsequently decreased as gestation progressed. AF potassium, chloride, and lactate concentrations initially decreased and then increased across gestation. Prior to day 9.5 and after day 18.5, AF volume was too small for volume or compositional determinations. CONCLUSIONS In the mouse, the rise in AF volume from mid gestation to a maximum late in gestation is similar to that in humans while the sharp fall prior to delivery is not. As observed in the fetal sheep, the changes in fluid volume are associated with AF osmolality and solute concentration changes that are correlated with advancing gestational age. These observations together with the feasibility of quantifying AF volume and composition in the mouse fetus demonstrate the possibility of using genetically altered mice as a model for future studies on the molecular mechanisms underlying the regulation of AF volume and composition.
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Affiliation(s)
- Cecilia Y Cheung
- Division of Perinatal Medicine, Department of Reproductive Medicine, University of California San Diego, La Jolla, California 92093-0802, USA.
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26
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Levy DS, Zielinsky P, Aramayo AM, Behle I, Stein N, Dewes L. Repeatability of the sonographic assessment of fetal sucking and swallowing movements. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2005; 26:745-9. [PMID: 16161177 DOI: 10.1002/uog.1868] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
OBJECTIVE To test the repeatability of sonography in the assessment of fetal sucking and swallowing movements. METHODS Eighty normal fetuses of pregnant women with no systemic abnormalities were examined sonographically at 30-38 weeks of gestation. Sucking and swallowing movements were observed for 15 min and the face was visualized in frontal and lateral views. The examinations were recorded for later analysis by two independent observers and the 95% limits of agreement (Bland and Altman) method was used for inter- and intraobserver comparison. RESULTS The mean +/- SD number of swallowing movements, sucking bursts and total sucking movements recorded by Observer 1 were 8.3 +/- 4.7, 9.9 +/- 9.3 and 35.8 +/- 48.0 and the equivalent values for Observer 2 were 8.2 +/- 4.8, 9.8 +/- 9.3 and 36.4 +/- 49.0, respectively. The mean (95% limits of agreement) interobserver difference was 0.1 (-1.4; 1.6), 0.1 (-2.2; 2.3) and -0.6 (-9.0; 7.9), and the mean (95% limits of agreement) intraobserver difference was 0.4 (-3.1; 3.9), 0.1 (-2.0; 2.2) and 1.0 (-10.7; 12.7) for swallowing movements, sucking bursts and total sucking movements, respectively. CONCLUSIONS The high degree of intra- and interobserver repeatability disclosed in the sonographic analysis of fetal sucking and swallowing movements supports the applicability of sonographic assessment in normal fetuses.
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Affiliation(s)
- D S Levy
- Fetal Cardiology Unit, Institute of Cardiology of Rio Grande do Sul/Fuc, Porto Alegre, Brazil.
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Adams EA, Choi HM, Cheung CY, Brace RA. Comparison of amniotic and intramembranous unidirectional permeabilities in late-gestation sheep. Am J Obstet Gynecol 2005; 193:247-55. [PMID: 16021087 DOI: 10.1016/j.ajog.2004.12.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
OBJECTIVE Amniotic fluid volume is regulated by the intrinsic modulation of intramembranous absorption. However, neither the mechanisms nor the rate-limiting barriers of this transport are known. We tested the hypothesis that the amnion is the rate-limiting barrier of intramembranous absorption by comparing unidirectional permeabilities of the amnion in vitro and the intramembranous pathway in vivo. STUDY DESIGN Unidirectional permeabilities to 99m technetium pertechnate or [14 C]inulin of fresh ovine amnion were measured in vitro in a Ussing chamber; the permeability-surface area products were calculated by the multiplication of the permeabilities by gestational age-specific amniotic surface areas. Unidirectional permeabilities of the intramembranous pathway of the 2 tracers were calculated from solute fluxes between amniotic fluid and fetal blood in chronically catheterized late-gestation fetal sheep. Statistical comparisons included t -tests, least squares regression, analysis of variance, and analysis of covariance. RESULTS In the isolated amnion in vitro, the ratio of permeabilities in the amniotic fluid to chorionic direction and the reverse direction was not significantly different from unity for 99m technetium pertechnate (1.03+/-0.10 [SE]; n=7) or [14 C]inulin (1.10+/-0.17; n=7). In contrast, in the in vivo preparation, the ratio of intramembranous permeabilities outward from the amniotic fluid and the reverse direction was greater than unity for 99m technetium pertechnate (2.10+/-0.34; n=8; P=.014) and [14 C]inulin (4.68+/-1.24; n=7; P=.025). The permeability-surface area product of 99m technetium pertechnate (2.18+/-0.79 mL/min) of the isolated amnion was similar to the in vivo intramembranous permeability (n=8) in the amniotic fluid to fetal blood direction (1.42+/-0.34 mL/min) and greater than that in the reverse direction (0.84+/-0.25 mL/min; P=.046). The permeability-surface area product of [14 C]inulin of the amnion (0.53+/-0.20 mL/min) was similar to intramembranous permeability (n=7) in the amniotic fluid to fetal blood (0.68+/-0.15 mL/min) direction and greater than that in the reverse direction (0.22+/-0.06 mL/min; P=.0097). CONCLUSION Solute transport across the ovine amnion depends on solute size and appears to be limited only by the amnion's passive diffusional properties. In vivo intramembranous transport similarly depends on solute size but is not exclusively a passive diffusional process because it is primarily unidirectional outward from the amniotic fluid. Although it is a major barrier, the amnion is not the only barrier and does not appear to be responsible for the unidirectional nature of intramembranous absorption. Thus, unidirectionality appears to be imparted by nonpassive mechanisms in non-amnion tissues, which most likely includes vesicular transport within the endothelial cells of the intramembranous microvessels.
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Affiliation(s)
- Elizabeth A Adams
- Department of Reproductive Medicine, University of California San Diego, La Jolla 92093-0802, USA
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Faber J, Anderson D, Hohimer R, Yang Q, Giraud G, Davis L. Function curve of the membranes that regulate amniotic fluid volume in sheep. Am J Physiol Heart Circ Physiol 2005; 289:H146-50. [PMID: 15749743 DOI: 10.1152/ajpheart.01284.2004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Seven singleton 120-day fetal lambs were prepared with a shunt from the lung to the gastric end of the esophagus, a bladder catheter, and multiple amniotic fluid and vascular catheters. The urachus was ligated. Beginning 7 days later, amniotic fluid volumes were determined by drainage, followed by replacement with 1 liter of lactated Ringer (LR) solution. Urine flow into the amnion was measured continuously. In 14 of 27 experiments, amniotic fluid volumes were determined again 2 days after the inflow into the amnion had consisted of urine only and in 13 experiments after the inflow of urine had been supplemented by an intraamniotic infusion of LR solution. Intramembranous absorption was calculated from the inflows and the changes in volume between the beginning and end of each experiment. The relations between absorption rate and amniotic fluid volume, the “function curves,” were highly individual. Urine production during the infusion of LR solution did not decrease, fetal plasma renin activity decreased ( P < 0.001), and amniotic fluid volume increased by 140% [SE (27%), P < 0.005], but the increase in the amniochorionic absorption rate of 411% [SE (48%), P < 0.001] was greater ( P < 0.005) than the increase in volume. Each of the seven fetuses was proven capable of an average intramembranous absorption rate that exceeded 4.5 liters of amniotic fluid per day. During the infusion of LR solution, the increase in the rate of absorption matched the rate of infusion (both in ml/h), with a regression coefficient of 0.75 ( P < 0.001). Thus, even for large amniotic fluid volumes, volume is not limited by the absorptive capacity of the amniochorion, and, at least in these preparations, the position of the function curve and not the natural rate of inflow was the major determinant of resting amniotic fluid volume.
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Affiliation(s)
- Job Faber
- Dept. of Physiology & Pharmacology, L334, Oregon Health and Sciences Univ., Portland, OR 97239, USA
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29
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Mann SE, Ricke EA, Torres EA, Taylor RN. A novel model of polyhydramnios: amniotic fluid volume is increased in aquaporin 1 knockout mice. Am J Obstet Gynecol 2005; 192:2041-4; discussion 2044-6. [PMID: 15970890 DOI: 10.1016/j.ajog.2005.02.046] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To test the hypothesis that amniotic fluid volume is increased in aquaporin 1 knockout mice. STUDY DESIGN Transgenic mice deficient in aquaporin 1 protein were generated by targeted gene disruption, as described previously. After a cesarean section was performed, intact, individual gestational sacs were removed from the uterus and weighed. Amniotic fluid volume, osmolality, and fetal and placental weights were determined. Data were analyzed by a 1-way analysis of variance for ranks; Dunn's post hoc test was used to analyze significant trends. RESULTS Analysis of 16 litters showed 35 wild-type, 52 heterozygote, and 33 aquaporin 1 knockout mice. The knockout mice had a greater volume of amniotic fluid and lower amniotic fluid osmolality than their wild-type and heterozygote counterparts. There were no significant differences in fetal or placental weights among the groups. CONCLUSIONS Aquaporin 1 null fetuses produce a greater volume of more dilute amniotic fluid. Our findings show that aquaporin 1 water channels in fetal membranes may contribute to amniotic fluid volume regulation. We speculate that idiopathic polyhydramnios may be associated with a deficiency of aquaporin 1 channels in human fetal membranes. Transgenic aquaporin 1 knockout mice provide a unique animal of polyhydramnios.
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Affiliation(s)
- Stephanie E Mann
- Department of Obstetrics, Gynecology, and Reproductive Sciences and Medicine, University of California, San Francisco, USA.
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Anderson D, Yang Q, Hohimer A, Faber J, Giraud G, Davis L. Intramembranous absorption rate is unaffected by changes in amniotic fluid composition. Am J Physiol Renal Physiol 2005; 288:F964-8. [PMID: 15821258 DOI: 10.1152/ajprenal.00407.2004] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Experiments were performed to determine the effect of amniotic fluid dilution on the rate of intramembranous absorption. Seven fetal sheep at 118 days gestation were instrumented with a shunt between the trachea and esophagus and arterial and venous vascular catheters. In addition, the urachus of the fetal bladder was ligated, and a catheter was placed in the bladder. Ligation of the urachus does not interfere with urine flow into the amnion. After 5 days of recovery, fetuses were randomly assigned to one of two protocols; all fetuses completed both protocols. In the fetuses in the control period, continuous urine flow measurement was begun. In the fetuses assigned to the isovolumic dilution protocol, continuous urine flow measurement was also begun and, in addition, amniotic fluid was continually exchanged with lactated Ringer solution on an isovolumic basis. After 3–4 days, fetal blood pressures and amniotic fluid volumes were determined. Amniotic fluid volumes were determined by drainage. Each fetus was then assigned to the remaining protocol. The presence of the tracheal-esophageal shunt and the ligation of the urachus allowed the rate of intramembranous absorption to be calculated. Isovolumic exchange showed no effect on fetal vascular pressures, blood-gas values, or urine production. We could demonstrate no effect of isovolumic dilution of amniotic fluid on its volume. However, we were able to demonstrate an inverse relationship between amniotic fluid volume and intramembranous absorption ( P < 0.02).
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Affiliation(s)
- D Anderson
- Department of Physiology and Pharmacology, Oregon Health and Sciences University, Portland, Oregon 97291, USA
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Yang Q, Davis L, Hohimer A, Faber J, Anderson D. Regulatory response to washout of amniotic fluid in sheep. Am J Physiol Heart Circ Physiol 2005; 288:H1339-43. [PMID: 15513961 DOI: 10.1152/ajpheart.00740.2004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To test the hypothesis that a substance present in the amniotic fluid could serve as a regulator of amniotic fluid volume, we drained and discarded amniotic fluid while replacing it with lactated Ringer solution that was isotonic to amniotic fluid. Seven ewes with singleton fetuses at 119 ± 1 days of gestation (mean ± SE) were instrumented with multiple indwelling catheters in the pedal artery, pedal vein, and amniotic cavity. During the exchange periods, an average of 3,019 ± 171 ml/day of lactated Ringer solution was infused into the amniotic cavity while an equal amount of amniotic fluid was pumped out and discarded. During the control period, amniotic fluid composition and volume were not altered. Exchange and control periods started with the same amniotic fluid volume, lasted 3 or 4 days, and were randomized with regard to order. Amniotic fluid volume measured by vacuum drainage was 556 ± 98 ml at the end of the control period and 986 ± 209 ml ( P = 0.03) at the end of the exchange period. Fetal arterial blood gases, hemodynamic parameters and the osmolality gradient between fetal plasma and amniotic fluid were not altered by the exchange process. A linear relationship between the control amniotic fluid volume and the volume at the end of the exchange period ( P = 0.003) suggests that the animals with larger control volumes responded to isovolumic dilution with a larger volume increase. We conclude that amniotic fluid may contain a substance that regulates amniotic volume.
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Affiliation(s)
- Qin Yang
- Department of Obstetrics and Gynecology, Oregon Health and Science University, Portland, Oregon 97291, USA
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Brace RA, Cheung CY. Amniotic fluid volume responses to amnio-infusion of amniotic fluid versus lactated Ringer's solution in fetal sheep. ACTA ACUST UNITED AC 2004; 11:363-8. [PMID: 15350248 DOI: 10.1016/j.jsgi.2004.02.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE The present study tested the hypothesis that an intra-amniotic infusion of amniotic fluid (AF) would produce a more sustained increase in AF volume than an infusion of lactated Ringer's solution. METHODS Five chronically catheterized, late-gestation fetal sheep were studied over two 5-day periods with AF volume measured daily. After baseline measurements on day 1, 1 L of either warmed, previously frozen AF or warmed lactated Ringer's solution was infused intra-amniotically over 60 minutes. Two days later, the other fluid was infused. During the second week, fluids were infused in the opposite order. Analysis of variance (ANOVA) was used for statistical testing. RESULTS Following intra-amniotic infusion (n = 20) of 1007 +/- 7 (SE) mL of either AF or Ringer's solution, intra-amniotic retention of the infused fluid was only moderate after 1 day (37.2% +/- 7.9%, P <.001) and was not significantly different from zero after 2 days (16.5% +/- 9.5%, P =.1). There were no significant differences in AF volume following infusion of AF versus lactated Ringer's solution or the order in which they were infused. AF compositional changes were similar except that pH and bicarbonate concentration were reduced as expected immediately after lactated Ringer's solution with a return to normal values after 1 day. AF lactate increased after lactated Ringer's solution infusion, declining to baseline values after 2 days. Fetal urine flow rate increased by 75% +/- 24% at 1 day postinfusion and there was no difference between infusates. CONCLUSIONS The expansion of AF volume over 2 days following amnio-infusion does not appear to depend on minor compositional differences or the presence of microconstituents such as hormones, cytokines, or growth factors that are normally present in AF.
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Affiliation(s)
- Robert A Brace
- Department of Reproductive Medicine, University of California San Diego, San Diego, California 92093-0802, USA.
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Brace RA, Vermin ML, Huijssoon E. Regulation of amniotic fluid volume: intramembranous solute and volume fluxes in late gestation fetal sheep. Am J Obstet Gynecol 2004; 191:837-46. [PMID: 15467551 DOI: 10.1016/j.ajog.2004.01.048] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
OBJECTIVE Recent studies suggest that amniotic fluid volume is regulated by the rate of intramembranous absorption of amniotic fluid into fetal blood. The purpose of the present study was to determine the simultaneous intramembranous solute and water fluxes to gain insight into the intramembranous transport and amniotic fluid volume regulatory mechanisms. STUDY DESIGN All major amniotic inflows and outflows, except intramembranous flow, were eliminated in 10 fetal sheep over 8 hours by occlusion of the fetal trachea and esophagus; the fetal urine was drained to the exterior. Amniotic fluid composition and volume were measured before and at the end of the 8 hours. Solute and volume fluxes through the intramembranous pathway were calculated from amniotic fluid concentration and volume changes. Statistical analyses included t-tests, linear regression, and analyses of variance. RESULTS Amniotic fluid volume decreased by 128 +/- 24 (SE) mL over 8 hours (P < .001), which was correlated only marginally with the fetal to amniotic fluid osmotic gradient (r=0.59; P = .072). Amniotic fluid sodium, chloride, calcium, and bicarbonate concentrations increased (P < .0001), even though there were net outward fluxes of these solutes; these outward fluxes occurred against concentration gradients; and the clearances of these solutes were the same despite widely differing amniotic fluid concentrations and fetal blood to amniotic fluid concentration gradients. With the use of multivariate regression, intramembranous solute fluxes separated into 2 components, which were a primary outward flux that correlated with the volume flux and a minor inward component that correlated with the fetal plasma to amniotic fluid concentration gradient for sodium, chloride, calcium (P < .001), and bicarbonate (P < .02). The concentration-dependent fluxes averaged approximately one third of the bulk fluxes and were in the opposite direction. CONCLUSION The poor correlation of amniotic fluid volume reduction with the fetal-to-amniotic fluid osmotic gradient shows that the primary mechanism that mediates intramembranous volume flow is not passive osmosis in the normal fetus under basal conditions. The strong correlations of solute fluxes simultaneously with volume flux and concentration gradients suggest that intramembranous solute fluxes are mediated by both bulk flow and passive diffusion. The small size of the passive component relative to the size of the bulk component suggests that intramembranous solute transfer is mediated primarily by bulk flow with a smaller and usually oppositely directed contribution by diffusion down concentration gradients. Bulk flow by vesicular transport is the only known physiologic transport mechanism that is compatible with these data, but it is not known whether this occurs in the amnion or intramembranous blood vessels or both.
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Affiliation(s)
- Robert A Brace
- Department of Reproductive Medicine, University of California San Diego, La Jolla, Calif 92093-0802, USA.
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Thurlow RW, Brace RA. Swallowing, urine flow, and amniotic fluid volume responses to prolonged hypoxia in the ovine fetus. Am J Obstet Gynecol 2003; 189:601-8. [PMID: 14520242 DOI: 10.1067/s0002-9378(03)00494-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Four days of hypoxia produce an extensive fetal polyuria with little change in amniotic fluid volume in the ovine fetus. We hypothesized that fetal swallowing and intramembranous absorption would increase with prolonged hypoxia to offset the polyuria. STUDY DESIGN After a 24-hour normoxic period, nine ovine fetuses were subjected to 4 days of hypoxia induced by lowering maternal inspired oxygen content. Seven fetuses were monitored for 5 days as normoxic time controls. Measurements included fetal swallowed volume by a computerized system with Transonic flow probes, urine production by gravity drainage, and amniotic fluid volume by an indicator dilution technique. Data were averaged over 12-hour intervals, and a three-factor repeated-measures analysis of variance was used for statistical testing. RESULTS During days 2 to 5, arterial oxygen tension was 20.7+/-1.1 (SE) mm Hg in the normoxic and 13.9+/-0.8 mm Hg in the hypoxic fetuses (P<.0001). Urine flow was unchanged over time in the normoxic fetuses and increased gradually from 693+/-88 to 2189+/-679 mL per day during hypoxia (P<.0001). The prehypoxia swallowed volume was similar in the two groups, averaging 447+/-95 mL per day. Although transiently decreased in eight of nine hypoxic fetuses, the 12-hour average swallowed volumes were not significantly different at any time in the hypoxic versus normoxic fetuses (P=.62). Amniotic fluid volume increased in the hypoxic fetuses relative to that in the normoxic fetuses (520+/-338 mL vs -226+/-136 mL, P<.01), although the increase was small (P<.01) relative to the excess volume of urine (4269+/-1306 mL). Estimated intramembranous absorption increased from 209+/-95 mL per day during normoxia to average 1032+/-396 mL per day during hypoxia. CONCLUSIONS The current study supports the concept that prolonged hypoxia produces a progressive fetal polyuria with relatively small changes in amniotic fluid volume. Concomitantly, hypoxia does not induce prolonged changes in fetal swallowing; rather, intramembranous absorption greatly increases, thereby preventing severe polyhydramnios.
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Affiliation(s)
- Ralph W Thurlow
- Department of Reproductive Medicine, University of California, San Diego, CA 92093, USA
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Daneshmand SS, Cheung CY, Brace RA. Regulation of amniotic fluid volume by intramembranous absorption in sheep: role of passive permeability and vascular endothelial growth factor. Am J Obstet Gynecol 2003; 188:786-93. [PMID: 12634658 DOI: 10.1067/mob.2003.160] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE During long-term intravascular fluid infusion in the ovine fetus, a large increase in fetal urinary flow rate occurs while amniotic fluid volume increases only slightly because of increased intramembranous absorption. The current study tested the hypotheses that passive intramembranous permeability increases in response to fetal intravascular saline solution infusion and that the increased intramembranous absorption occurs in parallel with an increase in vascular endothelial growth factor gene expression in the amnion, chorion, and placenta. STUDY DESIGN Chronically catheterized fetal sheep that average 126 +/- 1 (SE) days of gestation either were infused intravascularly with 7 L of normal saline solution over 3 days (n = 8 sheep) or served as time controls (n = 6 sheep). Amniotic fluid volume and fetal urinary flow rate were measured daily. Intramembranous diffusional permeability was estimated daily as being equal to the clearance of intra-amniotically injected technetium 99m. Vascular endothelial growth factor messenger RNA abundance in the amnion, chorion, and placenta was determined by Northern blot analysis. Statistical analyses included analysis of variance. RESULTS In the infused fetuses, amniotic fluid volume and urinary flow increased (P <.01) by 891 +/- 144 mL and 3488 +/- 487 mL per day, respectively, on infusion day 3 compared with no changes over time in the control fetuses. In the infused fetuses, estimated intramembranous absorption increased by 4276 +/- 499 mL during the 3-day infusion. Intramembranous technetium 99m permeability was similar over time in the two groups. In the infused group, vascular endothelial growth factor messenger RNA levels in the amnion, chorion, and placenta increased 2- to 4-fold compared with the control group (P <.001). CONCLUSION The up-regulation of vascular endothelial growth gene expression may mediate the increase in the intramembranous absorption that is induced by volume-loading diuresis; however, this does not occur by passive mechanisms. We speculate that vascular endothelial growth mediates the increased intramembranous absorption by increasing vesicular transport.
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Affiliation(s)
- Sean S Daneshmand
- Division of Perinatal Medicine, Department of Reproductive Medicine, University of California at San Diego, La Jolla 92093, USA
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D'Elia A, Pighetti M, Nappi C. Prenatal ultrasonographic appearance of esophageal atresia. Eur J Obstet Gynecol Reprod Biol 2002; 105:77-8. [PMID: 12270572 DOI: 10.1016/s0301-2115(02)00142-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The authors report a case of esophageal atresia (EA) to help define criteria for prenatal ultrasonographic diagnosis of this malformative pathology.
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Affiliation(s)
- A D'Elia
- Department of Obstetrics and Gynecology, "Federico II" University Medical School, via O. Fragnito 60, 80131, Naples, Italy
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de Lagausie P, Guibourdenche J, de Buis A, Peuchmaur M, Oury JF, Aigrain Y, Sibony O, Luton D. Esophageal ligature in experimental gastroschisis. J Pediatr Surg 2002; 37:1160-4. [PMID: 12149693 DOI: 10.1053/jpsu.2002.34463] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND/PURPOSE Recently, the authors have shown that in human fetuses suffering from gastroschisis, there is an amniotic fluid inflammatory response and that amniotic fluid exchange designed to disrupt the inflammatory loop seems to have a favorable impact on outcome. The authors, therefore, designed in the fetal sheep a model of gastroschisis in which amnioinfusion significantly improved the deleterious process. They hypothesized that regurgitation and presence of digestive enzyme in the amniotic fluid triggers and maintains the process of inflammation. METHODS To test this hypothesis, the authors used their model of gastroschisis in the fetal lamb combined with esophageal ligation and compared it with gastroschisis with or without amnioinfusion. RESULTS Of 34 fetuses operated on at midgestation (days 70 through 80), 11 died in utero or were stillborn, 8 had gastroschisis and amnioinfusion, 8 had gastroschisis and no amnioinfusion, and 7 had gastroschisis and esophageal ligation. There were 9 control fetuses. Fetuses were killed at day 145 by cesarean section. Extraabdominal bowels with fibrous peel were processed for histologic examination. Thickness of bowel muscularis (micrometers) was 82.7 +/- 19 for controls, 159 +/- 56 for the nonamnioinfused fetuses, 126 +/- 21 for the amnioinfused fetuses (P =.001), and 240 +/- 225.8 for fetuses with esophageal ligature combined with gastroschisis. The same results were obtained for thickness of serous fibrosis and plasma cell infiltration. Assay of amniotic fluid ferritin, lipase, and protein showed that only amnioinfusion lowered ferritin and protein to levels similar to those of controls, thus, illustrating its preventive effect on inflammation and that esophageal ligature did not prevent digestive enzyme presence in the amniotic fluid. CONCLUSION In this model of gastroschisis in the fetal sheep, ligature of the esophagus, which was supposed to protect the extruded bowel by preventing oral regurgitation of digestive enzymes and by creating a relative hydramnios, did not improve the inflammatory and deleterious process, which is best prevented by amnioinfusion.
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Affiliation(s)
- P de Lagausie
- Département de périnatologie, Hôpital Robert Debré, Paris, France
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Abstract
Swallowing of amniotic fluid and lung fluid inflow were eliminated in 10 chronically instrumented fetuses. The urachus was ligated, and fetal was urine drained to the outside. At the beginning and the end of 21 experiments of 66 +/- 5 (SE) h duration, all amniotic fluid was temporarily drained to the outside for volume measurement and sampling. Amniotic fluid osmolalities and oncotic pressures were experimentally controlled. Amniochorionic absorption of amniotic fluid depended strongly on the osmolality difference between amniotic fluid and fetal plasma (P < 0.001), but at zero osmolality difference there still was a mean absorption rate of 23.8 +/- 4.7 (SE) ml/h (P < 0.001). Absorption was unaffected by the protein concentration difference between amniotic fluid and fetal plasma, but infused bovine albumin in the amniotic fluid was absorbed at a rate of 1.8 8 +/- 0.4 g/h (P < 0.001), corresponding to a volume flow of fluid of 33.8 8 +/- 6.1 ml/h (P < 0.001). Fluid absorption in the amniochorion is driven in part by crystalloid osmotic pressure, but about 25 ml/h is absorbed by a path that is permeable to protein. That path has the physiological characteristics of lymphatic drainage, although no anatomic basis is known to exist for a lymphatic system in the amniochorion.
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Affiliation(s)
- J Job Faber
- Department Physiology and Pharmacology, School of Medicine, Oregon Health Sciences University, Portland, Oregon 97201, USA.
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Matsumoto LC, Bogic L, Brace RA, Cheung CY. Prolonged hypoxia upregulates vascular endothelial growth factor messenger RNA expression in ovine fetal membranes and placenta. Am J Obstet Gynecol 2002; 186:303-10. [PMID: 11854655 DOI: 10.1067/mob.2002.119806] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE In ovine fetuses, 4 days of hypoxia resulted in a large increase in urine flow, without the development of polyhydramnios, which suggests that intramembranous absorption of the amniotic fluid was enhanced. Because vascular endothelial growth factor is speculated to be a regulator of intramembranous absorption through increases of membrane vascularity and fluid transport, we hypothesized that hypoxia upregulated vascular endothelial growth factor gene expression in the fetal membranes. STUDY DESIGN Five near-term ovine fetuses that were subjected to 4 days of hypoxia and 5 age-matched time controls were studied. On day 4, the amnion, chorion, and placenta were collected for cellular localization and quantification of vascular endothelial growth factor messenger RNA and for the determination of vascular endothelial growth factor molecular forms that were expressed. The data were analyzed statistically with the use of t tests and 2-factor analyses of variance. RESULTS Vascular endothelial growth factor messenger RNA was expressed in the fetal membranes localized to the amniotic epithelium and chorionic cytotrophoblast, and to the villous cytotrophoblast of the placenta. In hypoxic fetuses, vascular endothelial growth factor messenger RNA levels in these cell layers were significantly increased compared with the controls. Five vascular endothelial growth factor molecular forms were identified with vascular endothelial growth factor(164) being the most abundant form expressed. The pattern of expression of the forms was not altered by hypoxia. CONCLUSION In the near-term ovine fetus, hypoxia induced vascular endothelial growth factor messenger RNA expression in the amnion, chorion, and placenta. This was associated with an increase in intramembranous absorption of amniotic fluid. We speculate that the increased intramembranous absorption was mediated by a vascular endothelial growth factor-induced increase in the transport of amniotic fluid into the fetal membranes.
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Affiliation(s)
- Larry C Matsumoto
- Division of Perinatal Medicine, Department of Reproductive Medicine, University of California at San Diego, L Jolla, CA 92093-0802, USA
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Wang S, Kallichanda N, Song W, Ramirez BA, Ross MG. Expression of aquaporin-8 in human placenta and chorioamniotic membranes: evidence of molecular mechanism for intramembranous amniotic fluid resorption. Am J Obstet Gynecol 2001; 185:1226-31. [PMID: 11717661 DOI: 10.1067/mob.2001.117971] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE The intramembranous pathway of amniotic fluid absorption has recently been recognized as a critical regulatory path for amniotic fluid resorption, which contributes importantly to amniotic fluid volume homeostasis. Yet, the underlying molecular and cellular mechanisms for water absorption across the amniotic membranes remain unknown. We hypothesize that amniotic fluid water is absorbed across aquaporin water channels in the chorioamniotic membranes. Recently the water channel aquaporin-8 complementary DNAs for mice, rats, and humans have been cloned; and aquaporin-8 has been found to be expressed in the placenta and in other organs. The objective of the present study was to determine whether aquaporin-8 is expressed in human chorioamniotic membranes. STUDY DESIGN Freshly frozen human amnion, chorion, placenta, and umbilical cord of a normal term pregnancy were used in this study. Reverse transcriptase-polymerase chain reaction was used to determine the aquaporin-8 gene expression. In situ hybridization with biotin-labeled aquaporin-8 riboprobe was undertaken to localize the cellular expression of aquaporin-8 gene in these human fetal membranes. RESULTS Using reverse transcriptase-polymerase chain reaction, we have demonstrated that aquaporin-8 is expressed in human amnion, chorion, and placenta. Further studies of in situ hybridization of aquaporin-8 identified aquaporin-8 gene expression in epithelial cells of chorion and amnion and of the syncytiotrophoblasts and outer layer trophoblasts of placenta. CONCLUSION This is the first study that demonstrates the expression of aquaporin-8 water channel in human chorioamniotic membranes. These results suggest that aquaporin-8 may be a water channel that mediates amniotic fluid resorption by way of the intramembranous pathway.
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Affiliation(s)
- S Wang
- Department of Obstetrics and Gynecology, Harbor-UCLA Research and Education Institute, School of Medicine, University of California, Los Angeles, USA.
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Matsumoto LC, Cheung CY, Brace RA. Increased urinary flow without development of polyhydramnios in response to prolonged hypoxia in the ovine fetus. Am J Obstet Gynecol 2001; 184:1008-14. [PMID: 11303213 DOI: 10.1067/mob.2001.112971] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE In the ovine fetus subjected to 24 hours of hypoxia, urinary flow is normal within a few hours from the onset of hypoxia and there is a maintained inhibition of swallowing. We hypothesized that 4 days of fetal hypoxia would lead to polyhydramnios. STUDY DESIGN Five late-gestation fetal sheep were subjected to hypoxia for 4 days and 7 other late-gestation fetal sheep served as time control animals. Fetal hypoxia was produced on postsurgical days 5 through 9 by continuous intratracheal nitrogen insufflation to the ewe. On days 3, 5, 7, and 9 after surgery, amniotic fluid volume, fetal urinary flow rate, and the compositions of maternal and fetal blood, amniotic fluid, and fetal urine were measured. A 3-factor analysis of variance was used for statistical analysis. RESULTS During the period of experimental hypoxia the mean (+/-SE) fetal PaO(2) was 16.0 +/- 0.6 mm Hg, versus 21.2 +/- 0.7 mm Hg in control sheep (P <.001). Fetal hypoxia was associated with increased urinary flow on days 7 and 9, averaging 1410 +/- 310 and 2101 +/- 345 mL/d, respectively, versus 585 +/- 92 and 699 +/- 78 mL/d, respectively, in control animals (P <.001). Amniotic fluid volume was unchanged with time and averaged 960 +/- 159 mL in hypoxic fetuses on postsurgical days 7 through 9 and 851 +/- 130 mL in control animals (P =.60). Fetal blood lactate increased in the hypoxic animals, averaging 3.4 +/- 2.1 mmol/L versus 1.6 +/- 0.3 mmol/L in control animals (P =.02). Fetal urinary excretions of sodium, potassium, chloride, and lactate increased significantly during hypoxia, by 170% to 400%. CONCLUSION Four days of nitrogen-induced hypoxia in the ovine fetus resulted in excess fetal urinary flow approximating 1000 mL/d greater than normal without the development of polyhydramnios. Because amniotic fluid volume did not change and hypoxia is a known inhibitor of fetal swallowing, we speculate that intramembranous absorption of amniotic water, electrolytes, and lactate increased.
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Affiliation(s)
- L C Matsumoto
- Division of Perinatal Medicine, Department of Reproductive Medicine, University of California at San Diego. La Jolla 92093-0802, USA
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Matsumoto LC, Bogic L, Brace RA, Cheung CY. Fetal esophageal ligation induces expression of vascular endothelial growth factor messenger ribonucleic acid in fetal membranes. Am J Obstet Gynecol 2001; 184:175-84. [PMID: 11174499 DOI: 10.1067/mob.2001.108340] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Obstruction of the fetal esophagus does not always produce the expected polyhydramnios. This is because of increased intramembranous absorption of amniotic fluid into the fetal circulation. A possible mediator for this increased absorption is vascular endothelial growth factor (VEGF). The present objective was to explore whether VEGF gene expression and action would be induced in fetal membranes and placentas of ovine fetuses after esophageal ligation. STUDY DESIGN Five late-gestation fetal sheep underwent esophageal ligation and 5 served as control animals. On postoperative day 9, amnion, chorion, and placenta were collected for cellular localization and quantitation of VEGF messenger ribonucleic acid by in situ hybridization and Northern blot analysis. Reverse-transcription polymerase chain reaction was used to identify the VEGF molecular forms. Immunostaining with Ki-67 antibody was used to determine the proliferation of vascular endothelium in the fetal membranes and placentas. RESULTS VEGF messenger ribonucleic acid was localized in amniotic epithelium, chorionic cytotrophoblast, and cytotrophoblast of the placenta. VEGF164 was the major transcript expressed in these tissues. The abundance of VEGF messenger ribonucleic acid in the amnion and chorion, but not in the placenta, was significantly increased in the ligated fetuses in comparison with the control fetuses. The proliferation of the intramembranous blood vessel endothelium was greater in the ligated fetuses than in the control fetuses. CONCLUSION The levels of VEGF messenger ribonucleic acid and the proliferation of vascular endothelium in the amnion and chorion increased after fetal esophageal ligation. This provides a possible mechanism for the enhanced intramembranous absorption of amniotic fluid through increased vascularity and permeability of the fetal membranes, thus ameliorating the development of polyhydramnios. We speculate that the signal(s) that mediate the increase in VEGF expression is present in either the fetal urine or the fetal lung secretions, or both.
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Affiliation(s)
- L C Matsumoto
- Division of Perinatal Medicine, Department of Reproductive Medicine, University of California at San Diego, 92093-0802, USA
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