Aging of the erythrocyte. V. Hydrolysis of fluorescein diacetate in red cells.

In contrast to situation found in other cell types, no linear dependence of product fluorescence vs time is observed when fluorescein diacetate (FDA) is hydrolysed by erythrocytes and hemolysates. The rate of hydrolysis is increased by high concentrations of sucrose suggesting a positive effect of viscosity on the rate of the reaction. These peculiarities can be explained by assumption of a two-step hydrolysis of FDA. The FDA-hydrolytic activity decreases with increasing cell density (age).