Permeability of Ehrlich Cells to Uracil, Thymine and Fluorouracil.

Abstract

Uracil, thymine and fluorouracil enter Ehrlich ascites cells by diffusion. The permeability constants at 5[degree]C were 1.2 x 10-5 cm/min for uracil; 3.2 x 10-5 cm/min for thymine; and 1.1 x 10-5 cm/min for fluorouracil. Accurate measurements could not be obtained at 39[degree]C because of the rapidity of the equilibration of the intracellular space, but estimates of 10-3 to 10-4 cm/min for the permeability constants at 39''C were obtained.