[The action of ionizing radiation on neuronal function in the edible snail. Phospholipase A2 and the Na+ and K+ transport systems]. / Deistvie ioniziruiushchei radiatsii na funktsional'noe sostoianie neironov vinogradnoi ulitki. Fosfolipaza A2 i sistemy transporta Na+ i K+.

A study was made of the influence of A2 phospholipase on 22Na release from cells of nerve ganglia of edible snail. The treatment of nerve ganglia with A2 phospholipase inhibits Na, K-pump of neuronal membranes and does not exert a substantial effects on Na/Ca metabolism. There is a similarity between the effects of ionizing radiation and A2 phospholipase on the release of 22Na from cells.

[Effect of ionizing radiation on the functional state of Helix pomatia neurons. The systems of Na+ and K+ transport]. / Deistvie ioniziruiushchei radiatsii na funktsional'noe sostoianie neironov vinogradnoi ulitki. Sistemy transporta Na+ i K+.

The influence of ionizing radiation (5.16 C/kg) on passive and active Na+ and K+ transfer within the giant neurons of edible snail (Helix pomatia) has been investigated. It has been shown that ionizing radiation increases passive permeability of membranes, inhibits active ion transport, changes the number and the affinity of functionally active Na+,K+-ATPase molecules. The authors discuss the mechanisms of action of ionizing radiation.

The effects of short-chain fatty acids on the neuronal membrane functions of Helix pomatia. III. 22Na efflux from the cells.

The effect of short-chain fatty acids on both ouabain-sensitive and ouabain-insensitive fractions of 22Na efflux from the neurons of Helix pomatia was studied. Fatty acids, having fewer than 10 carbon atoms in the hydrocarbon chain, increased the ouabain-sensitive 22Na efflux from the neurons, while fatty acids, having more than 9 carbon atoms, inhibited the 22Na efflux in comparison with that in normal physiological solution. All the fatty acids used had an inhibiting effect on the ouabain-insensitive 22Na efflux from the cells independent on the number of carbon atoms in the hydrocarbon chain. These studies indicate that these short-chain fatty acids can be effective modulators of both ouabain-sensitive and ouabain-insensitive fractions of Na efflux from the cells.

The effects of short-chain fatty acids on the neuronal membrane functions of Helix pomatia. II. Cholinoreceptive properties.

We have examined the effects of short-chain fatty acids on acetylcholine (ACh)-induced transmembrane currents using internally dialyzed neurons of Helix. Decenoic acid, which increased the fluidity of excitable membranes, caused dramatic changes in the voltage sensitivity of ACh currents consisting of an ACh-induced increase in membrane permeability for K+ and Na+ ions and a shift of the Erev of these ACh responses to more positive potentials. Valeric acid, which did not change the membrane fluidity, had no effect on this type of ACh response. Changes of the ENa and ECl had no effect on the size of the decenoic acid-induced shift of the Erev. But the influence of decenoic acid on the voltage sensitivity of ACh-induced currents almost disappeared after the change of the EK by the reduction of the internal K concentration. Decenoic acid had no effect on ACh responses in which K+ ions were not involved in the generation of ACh-induced currents. The results suggest that decenoic acid-induced changes in membrane fluidity modulate cholinoreceptive properties of the neuronal membrane by the inhibition of the K+ carrier involved in the generation of ACh responses.