[Elevation of serum glucose concentration after administration of 5'-AMP to rats and modulation of this process dynamics following single gamma-irradiation at 1 Gy dose].

Injection of exogenic 5'-AMP to rats was accompanied by pronounced and transient adenosinemediated elevation of serum glucose concentration. Both efficiency and duration of the observed hyperglycemic effect were increased within the first week after single whole-body gamma-irradiation (137Cs) of the animals at 1 Gy dose. These data suggest modification of purinergic regulation of some processes of carbohydrate metabolism and disturbance of the organism tolerance towards the glucose following 1 Gy gamma-irradiation.

[The acute action of gamma radiation at a dose of 1 Gy on the enzymatic activity of serum ATPase and ADPase].

Studies were carried out to investigate the activity of ATPase and ADPase in rat blood serum after strong (137Cs) on the rate of 1 Gy. Rats were examined for various postirradiation periods up to 3 months. Two-fold decreasing of serum ATPase activity was recorded within the two weeks after gamma-irradiation.

[Interaction of native 5'-ATP with rat liver cell membranes and adipose tissue].

Studies have been carried out to evaluate specific binding and enzymatic hydrolysis of native 5'-ATP by rat liver and adipose tissue plasma membranes. Addition of [14C]ATP to membranes resulted in sequential nucleotide hydrolysis occurring via stepwise enzymatic reactions: ATP-->ADP-->AMP-->adenosine, thus indicating a high ecto-phosphatase activity of the plasma membranes under study. The ATP-binding kinetic characteristics were studied using a high-speed filtration technique under complete inhibition of membrane nucleotidases by excess EDTA (40 mM).

[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.

[The physicochemical status of the plasma membranes of rat fatty tissue and liver in the late periods after gamma irradiation at a dose of 1 Gy. Structural changes in the membranes].

The structural status of plasma membranes of adipose tissue and liver of rats was investigated at remote times (from 15 to 380 days) after single 1-Gy gamma irradiation. The structural status was estimated by pyrene excimerisation parameters and also by both induction resonance energy transfer method and membrane tryptophan fluorescence spectral characteristics. On days 50-100 following irradiation the microviscosity of a lipid phase of membranes increased and the mode of lipid/protein interactions changed, whereas at later times the indices under study did not vary from the controls.