Studies of the isolated perfused human placenta

Summary Methods of perfusing the isolated, surviving human placenta under nearly physiologic circumstances are presented. During periods up to 12 hours, the rate of glucose utilization is about 1 Gm. per kilogram per hour. The production of organic acids causes a steady rise in hydrogen ion concentration with a parallel rise in potassium concentration. No conjugation of bilirubin with glucuronic acid could be observed. Hypoxia results in vasodilatation with increased rates of flow through the fetal vascular bed, whereas high oxygen pressures cause the reverse. It is believed that similar responses occur in utero. The fetal circulation is not responsive to epinephrine or norepinephrine but responds with vigorous vasoconstriction to serotonin and histamine.