Washout of xenon-133 from isolated guinea-pig placenta

The clearance curves of xenon-133 were registered with an external detector situated above the isolated, dually perfused guinea-pig placenta. The curves were analyzed with a computer program that calculated the parameters of a sum of exponentials. Fetal and maternal flow rates were varied systematically. It was attempted to relate subdivisions of the preparation and their flow rates to the results of washout analysis. No unequivocal correspondence between anatomical and calculated compartments could be detected, but mean calculated and real relative perfusion rates correlated reasonably well. It is concluded that the compartment analysis of xenon clearance curves is not advantageous to other methods.