Document Detail

Absence of fetal placental waterfall phenomenon in chronically prepared fetal lambs.
MedLine Citation:
PMID:  1267019     Owner:  NLM     Status:  MEDLINE    
An electromagnetic flow sensor was placed on the distal fetal aorta (umbilical flow fraction 78.1 +/- 1.6 SEM, %), an inflatable occluder was tied around the umbilical cord, and catheters were placed in distal branches of an umbilical artery and vein, a uterine vein, and in the amniotic cavity. An inflatalbe occluder was tied around the vagina of some of the ewes. Control values 3 days after surgery were (mean +/- SE): fetal femoral artery pH, 7.37 +/- 0.01; umbilical blood flow, 186 +/- 14 ml-min-1 .kg fetus-1; fetal arterial blood pressure, 39 +/- 3 mmHg; and umbilical venous pressure, 7.4 +/- 1.0 mmHg (above intrauterine pressure). Fetal weight at autopsy was 3.1 +/- 0.3 kg, n = 11. Small increases in umbilical vein pressure caused immediate decreases in placental blood flow without decreases in fetal arterial blood pressure. The relation between venous pressure and umbilical blood flow at constant arterial pressure was that of an inert system, i.e., no evidence of a surrounding pressure (Starling resistor effect or waterfall phenomenon) could be found with increases in venous pressures of 2-40 mmHg. The results were not affected by increases in uterine vein pressure between 2 and 30 mmHg, nor by anesthesia and supine position of the ewe, nor by ganglionic blockade of the fetal ANS. It was concluded that surrounding pressures in the fetal placental circulation could not be demonstrated.
K L Thornburg; J M Bissonnette; J J Faber
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  230     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1976 Apr 
Date Detail:
Created Date:  1976-07-06     Completed Date:  1976-07-06     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  886-92     Citation Subset:  IM    
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MeSH Terms
Blood Pressure*
Fetal Blood*
Fetus / physiology*
Placenta / blood supply*
Regional Blood Flow
Sheep / physiology*
Umbilical Arteries / physiology
Umbilical Veins / physiology

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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