The effect of elevated outflow pressure on flow resistance and the transfer of THO, albumin and glucose in the isolated guinea pig placenta.

In the isolated, artificially perfused guinea pig placenta the relationship between arterial pressures, venous pressures and the relative transfer of 3H2O, D-glucose and albumin was studied at constant arterial perfusion rates. The results were as follows: A. Elevation of the fetal venous pressure induces an increase of flow resistance at the maternal side. Fetal perfusion resistance is raised by elevated pressure in the uterine vein also, the effect is much more pronounced, however. B. When the outflow resistance increases, a net transfer of water especially from the fetal to the maternal side can be observed. The relationship between the venous pressure difference and the rate of filtration is non-linear. C. The fetomaternal transfer of 131J-albumin and of 3H2O resp. D-glucose is influenced by fetomaternal filtration to a different degree. Whereas the albumin transfer increases strongly, the transfer rates of tritiated water and glucose change little.