Transfer of Antipyrine, H2O, L-Glucose and α-Aminoisobutyric Acid Across the in Vitro Perfused Human Placental Lobe

The dual circuit in vitro perfusion of an isolated lobe of human placenta is a useful experimental technique to study transfer of material across the placenta and to identify factors influencing exchange between maternal and fetal circulation. It has repeatedly been noted that there is considerable variation in results among experiments which are not fully explained by differences in size of the perfused lobe (Schneider et al., 1972; Welsch, 1980). While flow rates in the two perfusion circuits can easily be controlled, the surface area of exchange, shunts, and degree of overlap of the two circulations remain major factors causing interexperimental variability. Antipyrine which rapidly equilibrates across most biological membranes has been proposed as a reference for normalization of experimental data on transfer (Dancis et al., 1973). After this correction parameters like membrane permeability or specific transport mechanisms can be explored. This concept should be valid for the study of test compounds which are similarly affected in transfer by the uncontrollable variables as is antipyrine.