Interrelationships of Perfusion Parameters in the Dual-Perfused Human Placental Cotyledon
The technique of in vitro dual-perfusion of an isolated human term placental cotyledon, in which intervillous space as well as fetal cotyledonary vasculture is perfused (Panigel, 1968; Schneider et al., 1972), has been widely used for study of placental uptake, metabolism and transfer (cf. Schneider and Dancis, 1985). We used this preparation to determine effects of vasoactive agents and drugs on resistance of the human fetoplacental vascular bed, carrying out pharmacological dose-response studies in which fetoplacental perfusion pressure was monitored (Hosokawa et al., 1985; Howard et al., 1986; Howard et al., in preparation). The preparation does not appear to have been used for physiological study of the regulation of human fetoplacental vascular resistance. With the objective of improving the understanding of hemodynamic characteristics of the dual-perfused placental cotyledon, we perfused the fetal circuit of preparations with a salt solution which had arterial gas and pH values similar to those reported for human umbilical arterial blood (Longo, 1972). Perfusion was standardized with the aid of fetal venous gas and pH analysis, and the relationship of the different perfusion parameters to each other were analyzed statistically. In particular, it was anticipated that the flow rate of maternal perfusate might be an important determinant of other perfusion parameters, because maternal blood is the source of oxygen and nutrients for placenta and fetus in vivo. Moreover, it was considered that examination of the interrelationship of perfusion parameters with fetal vascular resistance may indicate which parameters contribute to fetal vascular resistance and which may be indicators of the level of fetal resistance in the preparation.
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