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Foetal placental blood flow in the lamb
Author(s) -
Faber J. Job,
Green Thomas J.
Publication year - 1972
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1972.sp009853
Subject(s) - oncotic pressure , chemistry , blood flow , mean blood pressure , placenta , mean arterial pressure , blood pressure , osmotic pressure , fetus , endocrinology , medicine , anesthesia , pregnancy , biology , heart rate , biochemistry , albumin , genetics
1. Fifteen sheep foetuses of 1·5–5·2 kg body weight were prepared with indwelling arterial and venous catheters for experimentation one to six days later. 2. Unanaesthetized foetuses were found to have mean arterial and central venous blood pressures of 40 ± 1·5 ( S.E. of mean) and 2·0 ± 0·3 ( S.E. of mean) mm Hg respectively, compared to intra‐uterine pressure. Intra‐uterine pressure was 16 ± 0·8 ( S.E. of mean) mm Hg with respect to atmospheric pressure at mid‐uterine level. 3. Mean placental blood flow of the foetuses was 199 ± 20 ( S.E. of mean) ml./(min.kg body wt.). Mean cardiac output in eleven of the foetuses was 658 ± 102 ( S.E. of mean) ml./(min.kg). 4. Mean foetal and maternal colloid osmotic pressures were 17·5 ± 0·7 ( S.E. of mean) and 20·5 ± 0·6 ( S.E. of mean) mm Hg respectively at 38° C. 5. Intravenous infusions into six ewes of 1·8 mole of mannitol and 0·4 mole of NaCl resulted in significant increases in foetal plasma osmolarity, sodium, potassium, and haemoglobin concentrations, without detectable transfer of mannitol to the foetal circulation. 6. In the sheep placenta there is osmotic and hydrostatic equilibration of water. As a consequence, there should be an interaction between foetal placental blood flow and foetal water exchange with the maternal circulation. It was concluded that this interaction tends to stabilize foetal placental blood flow.