[Rat brain catecholamines in the initial period of acute radiation exposure].

Total X-ray irradiation (0.21 C/kg of rats induces an hour later an increase in the dopamine and norepinephrine content in the grey matter by 11 and 60%, respectively. The spontaneous release of dopamine and norepinephrine from the brain synaptosomes of the irradiated rats falls causing a decrease of the initial rate of the process.

[Acetylcholine in the brain of rats exposed to acute irradiation].

A two-fold increase in acetylcholine, that can randomly be released by brain synaptosomes, is registered 60 min following whole-body X-irradiation of rats with a dose of 0.21 C/kg; depolarization of the synaptosome membranes by potassium chloride increases the release of acetylcholine the augmentation of the release in this case being lower than that in the control. The initial rate of spontaneous neuromediator release from synaptosomes grows by 80 per cent whereas after depolarization of synaptosome membranes by potassium chloride, by 15 per cent.

[The cAMP system in the cerebral cortex of irradiated rats in increased exogenous K+ levels].

Treatment of grey matter of irradiated (0.21 Cl/kg) rats by 60 mM of KCl causing depolarization of cell membranes leads to the increase of the cAMP content and to the decrease of adenylatecyclase activity. Dynamics of the enzyme activity with an increase of the external KCl concentration in control is to a considerable extent similar to that after irradiation, though the latter is more pronounced and a time shift is observed for maximal increase of a cAMP content and cAMP phosphodiesterase activity.

[Metabolism of cGMP with K+ concentration increase in the medium causing depolarization of cortical cell membranes in normal and irradiated rats].

An increase in the K+ concentration in the medium to 60 mM which causes depolarization of cell membranes in the rat cerebral cortex is studied for its effect on the cGMP level, guanylate cyclase and cGMP phosphodiesterase activities in norm and one hour after X-ray irradiation. The cGMP content and guanylate cyclase activity in normal rats and 1 min after depolarization are shown to increase with the external K+ concentration. One hour after irradiation the activity of enzymes under examination is three times as high.

[Activity of Mg2+, Ca2+-ATPase and lipid concentration in the plasma membranes rat brain synaptosomes in the early stages of acute radiation injury].

It is established that an hour after total X-ray irradiation of animals in a dose of 0.21 C/kg the Ca2+ content increases in a homogenate and subcellular fractions of the nervous tissue. The activity of Mg2+, Ca2+-ATP-ase in synaptosome plasma membranes becomes 1.