Amniotic fluid volume response to esophageal occlusion in fetal sheep

Fujino, Yuji; Agnew, Connie L.; Schreyer, Peter; Ervin, M. Gore; Sherman, Dan; Ross, Michael G.

doi:10.1016/0002-9378(91)90005-c

Cited by 48 publications

(21 citation statements)

References 13 publications

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“…Some authors have disputed the role of fetal swallowing in the genesis of polyhydramnios, but their conclusions have been based on very limited studies over relatively short periods (Minei & Suzuki 1976, Wintour & Shandley 1993. Experimental oesophageal ligation has been reported to increase amniotic fluid volume in some (Fujino et al 1991), but not all, studies (Trahair & Harding 1995). Our finding that amniotic fluid volume was greater than 2 l (mean 5 l) in 10 of the 12 fetuses with oesophageal ligation lends support to the thesis that failure of fetal swallowing can be the cause of polyhydramnios.…”

Section: Discussionsupporting

confidence: 62%

Enteral IGF-I enhances fetal growth and gastrointestinal development in oesophageal ligated fetal sheep

Kimble¹,

Breier²,

Gluckman³

et al. 1999

Journal of Endocrinology

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Infants with upper gut atresia often have impaired intrauterine growth and gut function. IGF-I is important in fetal growth and is contained in amniotic fluid. We therefore wanted to test the hypothesis that IGF-I infused into fetal gut would reverse the effects of an upper gut obstruction on gut structure and growth in fetal sheep.At 90 days gestation fetuses (n=6 per group) underwent oesophageal ligation, followed by continuous infusion of IGF-I (1-8 µg/day) or saline into the gut beyond the ligation until 137 days. Controls underwent sham ligation only. Oesophageal ligation tended to reduce fetal body and organ weights. IGF-I treatment prevented this reduction and increased body length and spleen weight above those of controls. The decrease in bowel wall thickness induced by oesophageal ligation was also prevented by IGF-I treatment. Amniotic fluid IGF-I concentrations did not change over gestation and were higher in the IGF-I treated group. No change in fetal plasma IGF-I concentrations were detectable. We conclude that enterally administered IGF-I may enhance fetal growth and gut development in utero and that IGF-I in amniotic fluid may play a physiological role in gut development in the fetus.

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Section: Discussionsupporting

confidence: 62%

Enteral IGF-I enhances fetal growth and gastrointestinal development in oesophageal ligated fetal sheep

Kimble¹,

Breier²,

Gluckman³

et al. 1999

Journal of Endocrinology

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“…Catheters also were placed in the maternal femoral vein and artery. Animals were allowed Ն5 days for postoperative recovery, which included catheter maintenance and antibiotic administration (11).…”

Section: Surgical Preparationmentioning

confidence: 99%

“…This high rate of basal fetal swallowing is critical for the regulation of amniotic fluid volume (30) and the development of the fetal gastrointestinal tract. Disordered fetal swallowing has been associated with both a decrease (oligohydramnios) and an increase (polyhydramnios) in amniotic fluid volume (11,18). Both conditions are associated with a significant increase in perinatal morbidity and mortality, and limited treatment modalities are currently available.…”

mentioning

confidence: 99%

Neuronal NO modulates spontaneous and ANG II-stimulated fetal swallowing behavior in the near-term ovine fetus

El-Haddad

Chao

et al. 2002

American Journal of Physiology-Regulatory, Integrative and Comp

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. Neuronal NO modulates spontaneous and ANG II-stimulated fetal swallowing behavior in the near-term ovine fetus. Am J Physiol Regulatory Integrative Comp Physiol 282: R1521-R1527, 2002; 10.1152/ajpregu. 00229.2001.-Spontaneous fetal swallowing occurs at a markedly higher rate compared with spontaneous adult drinking activity. This high rate of fetal swallowing is critical for amniotic fluid volume regulation. Central NO is critical for maintaining the normal rate of fetal swallowing, as nonselective inhibition of NO (with central N G -nitro-L-arginine methyl ester) suppresses spontaneous and angiotensin II (ANG II)-stimulated swallowing. We sought to differentiate the contributions of central endothelial vs. neuronal NO in the regulation of spontaneous and stimulated fetal swallowing, using a selective neuronal NO synthase (nNOS) inhibitor. Six time-dated pregnant ewes and fetuses were chronically prepared with fetal vascular and intracerebroventricular (icv) catheters and electrocorticogram (ECoG) and esophageal electromyogram electrodes and studied at 130 Ϯ 1 days of gestation. After an initial 2-h baseline period (0-2 h), the selective nNOS inhibitor Npropyl-L-arginine (NPLA) was injected icv (2-4 h). At 4 h, the dose of NPLA was repeated, together with ANG II, and fetal swallowing was monitored for a final 2 h. Four fetuses also received an identical control study (on an alternate day) in which NPLA was replaced with artificial cerebrospinal fluid (aCSF). Suppression of nNOS by icv NPLA significantly reduced mean (Ϯ SE) spontaneous fetal swallowing (1.35 Ϯ 0.12 to 0.50 Ϯ 0.07 swallows/min; P Ͻ 0.001). Injection of ANG II in the presence of NPLA had no dipsogenic effect on fetal swallowing (0.68 Ϯ 0.09 swallows/min). In the aCSF study, icv aCSF did not change fetal swallowing (0.93 Ϯ 0.10 vs. 0.95 Ϯ 0.09 swallows/min), whereas icv ANG II resulted in a significant increase in the rate of fetal swallowing (2.0 Ϯ 0.04 swallows/ min; P ϭ 0.001). We speculate that the suppressive dipsogenic effects of central NPLA indicate that spontaneous and ANG IIstimulated fetal swallowing is dependent on central nNOS activity. amniotic fluid; angiotensin II THIRST AND APPETITE-MEDIATED ingestive behavior develop and are likely imprinted in utero, thus preparing for newborn and adult ingestive behavior. Fetal swallowing activity is markedly different from that of the adult, as basal fetal swallowing occurs at a markedly (6-fold) higher rate compared with basal adult drinking activity after body weight differences are adjusted for (35). This high rate of basal fetal swallowing is critical for the regulation of amniotic fluid volume (30) and the development of the fetal gastrointestinal tract. Disordered fetal swallowing has been associated with both a decrease (oligohydramnios) and an increase (polyhydramnios) in amniotic fluid volume (11, 18). Both conditions are associated with a significant increase in perinatal morbidity and mortality, and limited treatment modalities are currently available. However, the mechanisms under...

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“…The most significant sources of fluid are fetal urine and lung fluid secretions, whereas the loss of fluid occurs primarily through swallowing and intramembranous absorption (1)(2)(3)8). Intramembranous absorption refers to the movement of fluid from the amniotic fluid into the fetal blood perfusing the amnion and chorion (11) and ranges from ϳ250 to 500 ml/day (8). While intramembranous absorption rate will change in response to a variety of fetal perturbations including hypoxia (13,16), esophageal ligation (9), and changes in the osmotic gradient between the fetal plasma and the amniotic fluid (7), the basis for any regulatory control over the intramembranous absorption rate is unknown.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Intramembranous absorption rate is unaffected by changes in amniotic fluid composition

Anderson¹,

Yang²,

Hohimer³

et al. 2005

American Journal of Physiology-Renal Physiology

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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 Ͻ 0.02).fetal fluid balance THE RATE OF CHANGE IN VOLUME of amniotic fluid is determined by the difference between the inflow of fluid and the outflow of fluid into the amniotic space. The most significant sources of fluid are fetal urine and lung fluid secretions, whereas the loss of fluid occurs primarily through swallowing and intramembranous absorption (1)(2)(3)8). Intramembranous absorption refers to the movement of fluid from the amniotic fluid into the fetal blood perfusing the amnion and chorion (11) and ranges from ϳ250 to 500 ml/day (8). While intramembranous absorption rate will change in response to a variety of fetal perturbations including hypoxia (13, 16), esophageal ligation (9), and changes in the osmotic gradient between the fetal plasma and the amniotic fluid (7), the basis for any regulatory control over the intramembranous absorption rate is unknown.The present series of experiments was designed to test the hypothesis that the rate of intramembranous absorption is independent of the composition of the amniotic fluid. The contribution of intramembranous absorption was isolated by continually measuring urine flow and eliminating the contributions of lung fluid secretion and fetal swallowing through creation of a fistula between the esophagus and the trachea. Under these conditions, the composition of the amniotic fluid is dependent on the contribution of the urine flow and the contribution of diffusional exchange between the amniotic fluid and the fetal plasma. In an attempt to determine whether the ...

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Amniotic fluid volume response to esophageal occlusion in fetal sheep

Cited by 48 publications

References 13 publications

Enteral IGF-I enhances fetal growth and gastrointestinal development in oesophageal ligated fetal sheep

Enteral IGF-I enhances fetal growth and gastrointestinal development in oesophageal ligated fetal sheep

Neuronal NO modulates spontaneous and ANG II-stimulated fetal swallowing behavior in the near-term ovine fetus

Intramembranous absorption rate is unaffected by changes in amniotic fluid composition

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