title: Changes of fluoresceindiacetate-hydrolysis and transport in mammalian cells after ultra-violet- and gamma irradiation.
abstract: Changes in the permeability of cell membranes and in the enzymatic activity of intact cells and their homogenates after irradiation were studied. CHO-cells, erythrocytes and their homogenates were irradiated with cobalt-gamma radiation and UV-light. It was found that the esterases are more radio-sensitive in intact cells than in the corresponding homogenates. The decrease of the enzymatic activity after irradiation can be described by a one-hit curve, whereas the loss of transport activity can be resolved into two one-hit curves. The slope associated with the more sensitive target mainly determines the course of the composed transport curve. Mechanisms for the decreases in the rate constants are discussed.
mesh_terms: D002265:Carboxylic Ester Hydrolases / Q000378:metabolism / Q000528:radiation effects; D002460:Cell Line; D002463:Cell Membrane Permeability / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D004912:Erythrocytes / Q000201:enzymology / Q000528:radiation effects; D005452:Fluoresceins / Q000378:metabolism*; D005720:Gamma Rays; D006801:Humans; D006868:Hydrolysis; D066298:In Vitro Techniques; D011830:Radiation Effects; D014466:Ultraviolet Rays
chemical_list: D005452:Fluoresceins; D002265:Carboxylic Ester Hydrolases