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Stimuli for fetal swallowing: systemic factors
M G Ross1, D J Sherman, M G Ervin
1Department of Obstetrics and Gynecology, Harbor--University of California, Los Angeles Medical Center, Torrance 90502.
American Journal of Obstetrics and Gynecology
|December 1, 1989
Summary
Fetal lambs respond to thirst by increasing swallowing, indicating intact regulatory mechanisms. This suggests that in-utero stimuli can influence fetal swallowing and amniotic fluid volume.
Area of Science:
- Physiology
- Developmental Biology
- Perinatology
Background:
- The fetal gastrointestinal tract is a primary site for amniotic fluid absorption.
- Regulation of fetal swallowing, crucial for amniotic fluid balance, is not well understood.
Purpose of the Study:
- To investigate the acute regulation of ovine fetal swallowing in response to thirst stimuli.
- To determine if plasma hyperosmolality and angiotensin II affect fetal swallowing.
Main Methods:
- Developed a model for studying ovine fetal swallowing using electromyograms, esophageal flow probes, and computer analysis.
- Administered intravenous angiotensin II infusions and hypertonic saline injections to fetal lambs (131 +/- 2 days gestation).
- Monitored fetal blood pressure, plasma osmolality, swallowing activity, and esophageal flow.
Main Results:
- Angiotensin II infusion increased fetal blood pressure but did not alter swallowing rates.
- Hypertonic saline injection increased fetal plasma osmolality and significantly stimulated fetal swallowing and esophageal flow within one minute.
- Swallowing activity returned to basal levels within five minutes post-injection.
Conclusions:
- Ovine fetuses at 130 days' gestation exhibit intact responses to osmolar thirst challenges.
- Fetal swallowing, a key determinant of amniotic fluid volume, is responsive to in utero osmotic stimuli.