TY - JOUR
T1 - Increased urinary flow without development of polyhydramnios in response to prolonged hypoxia in the ovine fetus
AU - Matsumoto, Larry C.
AU - Cheung, Cecilia Y.
AU - Brace, Robert A.
N1 - Funding Information:
Supported in part by United States Public Health Service Awards HD35890 and HD33054 from the National Institute of Child Health and Human Development.
Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2001
Y1 - 2001
N2 - 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 Pao2 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.
AB - 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 Pao2 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.
KW - Amniotic fluid
KW - Hypoxia
KW - Intramembranous absorption
KW - Renal function
KW - Sheep
KW - Urinary flow
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U2 - 10.1067/mob.2001.112971
DO - 10.1067/mob.2001.112971
M3 - Article
C2 - 11303213
AN - SCOPUS:0035061995
VL - 184
SP - 1008
EP - 1014
JO - American Journal of Obstetrics and Gynecology
JF - American Journal of Obstetrics and Gynecology
SN - 0002-9378
IS - 5
ER -