[Structural and functional changes in plasma membranes of rat adipose tissue after chronic gamma-irradiation at a dose of 1 Gy].

The structural (microviscosity, lipid-protein interactions, lipid composition) and functional (5'-nucleotidase properties) status of rat adipose plasma membranes was studied 4, 10 and 30 days after prolonged gamma-irradiation at 1 Gy dose (period of exposure 94 days). The relative content of unsaturated fatty acids of the membrane phospholipids from irradiated rats was decreased during the period under study, whereas cholesterol/phospholipid molar ratio and pyrene excimerization parameter remained unchanged. Efficiency of the inductive-resonance energy transfer from the membrane tryptophenyls to pyrene was raised at 10 days postirradiation indicative on the lipid-protein alterations within membrane matrix, gamma-irradiation was characterized by the following features of 5'-nucleotidase; (1) two-fold increasing of Michaelis constant Km and (2) raising by 3-4 degrees C of the breakpoint on the enzyme Arrhenius plot. Scatchard parameters of 3H-AMP binding to the irradiated plasma membranes (measured by rapid filtration technique) were not different from the control ones.