The umbilical blood flow in the foetal sheep

Cooper, K. E.; Greenfield, A. D. M.; Huggett, A. St. G.

doi:10.1113/jphysiol.1949.sp004319

Cited by 38 publications

(16 citation statements)

References 6 publications

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“…The Cooper et al [1949] with their fetal plethysmograph, for in both series the ewes were given a spinal anaesthetic and placed on their back. To this end we have plotted their data and ours together in fig.…”

Section: Resultsmentioning

confidence: 99%

The Diffusibility of Oxygen Across the Sheep Placenta

et al. 1965

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Estimates have been made of: (1) the oxygen tension in blood samples drawn from unanesthetized ewes and their fetuses via chronic catheters in the uterine vein, umbilical artery and umbilical vein between 90 days and full term; (2) the rate of oxygen uptake by the umbilical circulation between 80 and 134 days in a series of anesthetized ewes, and (3) the 'diffusing capacity' of the placenta for oxygen in eleven anesthetized ewes in stages of gestation from 81 to 134 days. The results demonstrate: (1) there is no regular change with advancing gestation in the oxygen tension of the blood in the vessels sampled, and (2) the quantity of oxygen taken up by the umbilical blood and the 'diffusing eapacity' of the placenta for oxygen both increase as the fetal weight.As we explained earlier our interest in the permeability of the placenta of the ewe to oxygen, in the period 80 days to full term, grew out of two conflicting lines of evidence. One suggests that the permeability of the placenta and the weight of the cotyledons both reach a maximum about 100-110 days, the other that the permeability to oxygen increases with the fetal requirements as gestation advances beyond the 100th day. Data bearing on the question have been obtained through observations on: (1) the transplacental difference in oxygen tension; (2) the rate at which oxygen crosses the placenta relative to the fetal weight, and (3) the 'diffusing capacity' of the placenta for oxygen. These data are complementary and taken together support the second alternative. MATERIAL AND METHODS(1) The Transpiacental Difference in Oxygen Tension. -Pure bred Dorset ewes, at known stages in gestation, were used in all the experiments reported here. The uterine and umbilical bloods for the estimation of the transplacental difference in P02 were obtained via indwelling catheters [Meschia et at., 1959;.For each estimation two samples were drawn from a single vessel, one of 1-6 ml. into 0-4 ml. of an isotonic heparin-fluoride mixture, a second of 2 ml. (4 ml. from a maternal vessel) into an oiled glass syringe. The pH of the first was measured at room temperature with a glass electrode and a Beckman meter (model G); the result was corrected to 380 by subtracting 0*015 pH units for each degree below 380 at which the measurement was made. The oxygen content of the second sample was determined in duplicate on 0*5 ml. with the Van Slyke-Neil apparatus. The oxygen capacity was.calculated from the optical density at 530 my, of blood diluted 1 to 250 parts with distilled water and alkalinized with ammonia. The colorimeter was standardized with sheep blood saturated with oxygen in a Barcroft tonometer before the content * U.S.P.H. Fellow -present address:

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Section: Resultsmentioning

confidence: 99%

The Diffusibility of Oxygen Across the Sheep Placenta

et al. 1965

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“…Fig. 6 combines our observations on umbilical flow, made soon after delivery, on lambs of large breeds (14 Hampshire, 4 Suffolk and 1 Kerry Hill) with those of Cooper, Greenfield & Huggett (1949) plotted against gestation age using the data of Cooper, Greenfield & Huggett, 1949 (0, ---) and our observations (, -). The thin continuous curved line indicates the weight increase % per day (ordinates on the right), calculated as described in the text.…”

Section: Oxygen Tension and Oxygen Consumptionmentioning

confidence: 99%

Oxygen consumption and the arterial oxygen saturation in foetal and new‐born lambs

Acheson¹,

Dawes²,

Mott³

1957

The Journal of Physiology

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“…respectively, and the one of most suitable size selected for the individual foetus. The volume changes in the plethysmograph were transmitted to a soap-bubble recorder (Greenfield, 1948) and the movements of the bubble recorded photographically. One cm.…”

Section: Methodsmentioning

confidence: 99%