Julian R. Cotter

Placental transfer of iron.

Abstract The placental transfer of iron together with the uterine blood flow and oxygen consumption of the uterus and its contents were determined in pregnant rabbits in the latter third of gestation. The data demonstrate that the maternal plasma iron turnover is greatly increased in the last days of gestation and, in large measure, is directed to the developing fetuses. The placental transfer of iron proceeds at a constant rate, is independent of the concentration of iron in the maternal plasma, and depends on an active fetal circulation. The increase in iron transfer to the fetus occurs at a time when the fetuses are being subjected to a progressive decrease in available oxygen.

Observations on pregnancy at altitude

We have compared the oxygen, carbon dioxide, and hydrogen ion concentrations of pregnant sheep and goats at sea level with those obtained in the same animal in an altitude chamber at 5,000, 10,000, and 15,000 feet. By using indwelling plastic catheters, the changes which occur in the uterine circulation (and in a single instance, in the umbilical circulation) have been observed under conditions shown to be compatible with a live fetus. The effect of altitude upon the transplacental oxygen and carbon dioxide pressure gradients has been estimated and the results discussed in terms of the physiologic adaptations of the pregnant animal to an acute reduction in oxygen tension.

Blood flow and oxygen consumption of pregnant goats

Abstract The antipyrine method was employed for measuring the rate of blood flow per kilogram of tissue in the pregnant uterus of unanesthetized and apparently unstressed goats. The data were known with certainty to be compatible with the continued growth and development of the fetus. Uterine blood flow was high in early gestation but fell to a plateau of 354 ml. per kilogram per minute after the sixtieth day. Rate of O 2 consumption per kilogram was minimal in the first 2 months and then rose to a plateau of 8.1 ml. per kilogram per minute.

A study of the oxygenation of the fetus and newborn and its relation to that of the mother

Abstract This report deals with oxygen concentrations in maternal (artery and uterine vein), fetal (umbilical vein and artery), and newborn (umbilical artery) blood samples. Studies were made in 63 pregnant women at term, not in labor, and delivered by cesarean section. The results indicate a wide range of variation in the various samples. Data are also included for calculation of respiratory quotient and coefficient of oxygen utilization across the intact uterus. No relationship was found between Apgar scoring and percentage oxygen saturation in fetal vessels and blood in newborn infants.

Umbilical blood flow in late gestation: A comparison of simultaneous measurements with two different techniques

Abstract The umbilical blood flow of the fetus in utero has been estimated in near-term ewes by two methods based on different assumptions and techniques: (1) by equating it with the quotient of the decrease in maternal oxygen consumption which followed interruption of the umbilical circulation divided by the umbilical venoarterial oxygen difference and (2) by the diffusion equilibrium technique using antipyrine as the test substance. The results obtained are in good agreement. The mean values are 278 and 274 ml. per kilogram per minute, respectively.

Observations on pregnancy at altitude: II. Transplacental pressure differences of oxygen and carbon dioxide☆☆☆

Abstract The oxygen and carbon dioxide contents and tensions have been determined in the maternal arterial, uterine venous, umbilical arterial, and imbilical venous blood in pregnant ungulates bred and pastured at sea level and then exposed to altitudes as high as 15,000 feet. At altitude, the oxygen tension in the umbilical blood vessels decreases less than in the maternal placental vessels. Despite a smaller transplacental difference in oxygen pressure, the carbon dioxide pressure difference remains unchanged from sea level.

Blood flow and gaseous metabolism of the rabbit uterus during pregnancy.

Abstract Using indwelling plastic catheters, blood samples were drawn from an artery and a uterine vein of anesthetized and unanesthetized rabbits at selected stages in gestation. Oxygen content and oxygen capacity were determined on the samples. The coefficient of oxygen utilization by the uterus increased from an average value of 15 per cent early in gestation to 63 per cent in the last few days of the gestation period. The antipyrine method was employed for measuring the rate of blood flow per kilogram of tissue. Uterine blood flow was high in early pregnancy and decreased as gestation advanced. The rate of O 2 consumption per kilogram remained unchanged from the eleventh week onward; the average value was 7.42 c.c. per kilogram per minute.

Oxygen, carbon dioxide, and hydrogen ion concentration in arterial and uterine venous blood of pregnant goats

Abstract Using indwelling plastic catheters, blood samples were drawn from an artery and a uterine vein of unanesthetized pregnant goats at selected stages in gestation. Oxygen and carbon dioxide contents, pH, and oxygen capacity were determined on the samples. The coefficient of oxygen utilization by the uterus increased from 9 per cent early in gestation to 25 per cent in the last third of the gestation period of 145 to 147 days. The CO 2 tension of the arterial blood ranged between 25.1 and 31.9 mm. Hg (average, 28.6) and the pH was 7.32 to 7.49 (average, 7.41).

Uterine blood flow and oxygen consumption of the pregnant uterus of the Macaca mulatta

Abstract The antipyrine method was employed for measuring the rate of blood flow per kilogram of tissue in the pregnant uterus of unanesthetized and recently stressed Macaca mulatta. There is a trend toward a decreased flow with advancing pregnancy of approximately 250 c.c. per kilogram per minute at 80 days to about 140 c.c. per kilogram per minute near term. The oxygen consumption of the uterus and its contents shows no trend to change from 75 days onward. These findings are associated with a decrease in uterine venous percentage oxygen saturation and an increase in the coefficient of oxygen utilization by the uterus.

Ferrokinetics in pregnancy: I. Fetus and newborn

Abstract Ferrokinetic studies of the goat fetus in utero are presented and are compared to studies in the newborn goat at 24 and 48 hours of age. The hematocrit, serum iron, and plasma iron disappearance half-time have been determined. Based on the observation of a markedly elevated serum iron concentration and shortened radio iron disappearance in the fetus, the major finding is that of a greatly increased plasma iron turnover of the fetus in utero as compared to that of the newborn goat.