Fetal swallowing: response to systemic hypotension.
The fetal swallowing and endocrine responses to systemic hypotension were studied in five chronically instrumented ovine fetuses (125 +/- 2 days). Fetuses were prepared with bipolar electrodes inserted in the thyrohyoid muscle, nuchal esophagus, and thoracic esophagus, a flow probe surrounding the thoracic esophagus, and arterial and venous catheters. In response to an intravenous infusion of sodium nitroprusside, fetal mean arterial blood pressure decreased from 50.8 +/- 3.6 to 41.7 +/- 3.8 mmHg. Fetal plasma renin activity (5.0 +/- 1.4-25.1 +/- 10.3 ng.ml-1.h-1) and arginine vasopressin (5.6 +/- 4.5-26.3 +/- 21.0 pg/ml) increased, while fetal swallowing electromyogram activity (7.3 +/- 1.1-1.9 +/- 0.3 swallows/10 min) and esophageal flow (5.5 +/- 3.1-1.2 +/- 0.9 ml/10 min) significantly decreased during the nitroprusside infusion. These results indicate a suppression of fetal swallowing in response to systemic hypotension despite stimulation of the renin-angiotensin system.
Ross
M G
MG
Department of Obstetrics and Gynecology, Harbor-University of California, Los Angeles, Torrance 90509.
Sherman
D J
DJ
Ervin
M G
MG
Day
L
L
Humme
J
J
D000818:Animals; D001127:Arginine Vasopressin / Q000097:blood; D003679:Deglutition / Q000502:physiology*; D004576:Electromyography; D004947:Esophagus / Q000503:physiopathology; D005260:Female; D005312:Fetal Blood / Q000378:metabolism / Q000502:physiology; D005333:Fetus / Q000502:physiology*; D006439:Hemodynamics; D007022:Hypotension / Q000097:blood / Q000139:chemically induced / Q000503:physiopathology*; D009334:Neck Muscles / Q000502:physiology; D009599:Nitroprusside; D011247:Pregnancy; D012083:Renin / Q000097:blood; D012756:Sheep
D001127:Arginine Vasopressin; D009599:Nitroprusside; D012083:Renin