IN VITRO STUDIES WITH 16-C14-ESTRONE: DISTRIBUTION BETWEEN PLASMA AND RED BLOOD CELLS OF MAN*

Abstract

When 16-C14- estrone was added to blood samples of normal individuals, 75 .0 - 88.4% of the radioactivity was recovered in the plasma; the balance of the activity accompanied the red cells. Neither the length of the incubation (0-4 hours) nor temperature (5, 22 and 37[degree]C.) appeared to influence this distribution. The activity accompanying the red cells was slowly removed by successive washings with 0.9 % NaCl solution, the average distribution coefficient of 16-C14- estrone for this system being 0.094 - 0.125. The activity was removed much faster by plasma, the average coefficient being 3.09 - 3.29. It was calculated that the solubility of estrone in red cells was at least 6.08 x 10-5 [image]/l and probably greater since overloading was not achieved. The average distribution coefficient of radioestrone between 0.9 % NaCl solution and red cell stroma was 0.095, while that between a saline solution of 25% hemoglobin and red cells was 0.247. The suggestion that the phenomena studied were related to adsorption of estrone on the red cell surface was discussed.