The rate of clearance of xenon from rat liver sections in vitro and its significance in relation to intracellular diffusion rates

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Abstract
The measurements were made following exposure of the sections to air containing the radioactive xenon for periods sufficiently long to allow equilibrium to occur. After an initial rapid clearance phase, clearance in each case was exponential. The halving times ranged from two seconds for the 50 mu m section to 250 s for the 670 mu m section. The thin section results showed that clearance from individual cells must be less than two seconds. In blood flow studied the clearance halving time from highly perfused tissues is an order of magnitude greater than this. Hence the present study does not support the view that intracellular diffusion limits the rate of blood-tissue gas exchange. The present study yielded a value of (3.8+or-0.7)*10-6 cm2 s-1 for the bulk diffusion coefficient of xenon in rat liver at 37 degrees C, and showed that the diffusion coefficient of xenon in cytoplasm must be greater than 2.2*10-8 cm2 s-1.