Thermodynamic network modelling of transfer across the perfused guinea-pig placenta, using SPICE

The response of the dually perfused guinea pig placenta to bolus inputs of the marker substances 125I-albumin and tritiated water is used to model vascular placental topology and membrane characteristics. This is accomplished by generating a thermodynamic network containing ten adjustable variables describing flow and transfer quantitatively. After translation of the network into an electronic circuit the parameter values are determined with the use of the SPICE program. The results are then used to estimate unknown physiological variables like shunted flow, membrane permeabilities, etc. This model has potential usefulness in the study of those areas of placental physiology in which transient analysis is required.