[The amiridin and tacrine modulation of the cholinoreceptor activity and plasticity of snail neurons: the phenomenology and mechanisms]. / Moduliatsiia ampiridinom i takrinom aktivnosti i plastichnosti kholinoretseptorov neironov vinogradnoi ulitki: fenomenologiia i mekhanizmy.

The effects of amiridine and tacrine on the membrane potential, activity and plasticity of cholinoreceptors have been studied using the recording of intracellular and transmembrane currents in identified neurons of Helix lucorum. Amiridine and tacrine (1-100 mcM) have no noticeable effects on the membrane potential of the cells. Both compounds modulate the activity of cholinoreceptors to judge from their influence on the inward current induced by the local acetylcholine (ACh) application: they increase the duration of the current with a two-phase effect on the amplitude (a short-latent intensification with a following decrease). Amiridine and tacrine intensify ACh current extinction induced by repeated ACh application to the soma. Acetylcholinesterase inhibitor physostigmine has a similar modulating effect on ACh current and its extinction. It impedes the modulating effects of amiridine and tacrine. Amiridine and physostigmine directly affect cholinoreceptors and ion channels controlled by them changing in a similar way the current-voltage curves of ACh-current and approximating it to the equilibrium potential of chloride ions. Modulating effects of amiridine, tacrine and physostigmine on the activity and plasticity of cholinoreceptors may be supposed to be caused by their direct membrane-cytoplasmic action.

[The effect of amiridin and tacrine on the potassium currents in a nerve fiber]. / Vliianie amiridina i takrina na kalievye toki v nervnom volokne.

The experiments on isolated nerve fibers from the frog Rana ridibunda have demonstrated that aminoacridine tacrin and aminocholine amiridine given in a concentration of 1 microM induced a 3-4 mV increase in the resting potential of the intact Ranvier nodal membrane depolarized by several millivolts by external source current, accompanied by a rise in the amplitude and curvature of action potential. With the voltage clamp, the two agents shifted a steady state potassium conductivity vs. the voltage curve measured in the vicinity of the resting potential in isotonic KCl solution. The shift had a hyperpolarizing direction and magnitude of 1-2 mV at the agents' concentrations of 0.01-0.1 microM and 10 mV at concentrations higher than 1 microM. The resting potential change calculated on the basis of conductivity measurements was in agreement with that observed experimentally. It is suggested that the tacrin- and amiridine-induced shift of the voltage sensitivity region of potassium channels near the resting potential might underlie their therapeutic effects in patients with senile dementia of the Alzheimer type.

[The effect of amiridin on the spectral characteristics of the human EEG]. / Vliianie amiridina na spektral'nye kharakteristiki EEG cheloveka.

EEG testing of 28 healthy males showed that amiridine (two tablets, each 20 mg, orally at a 45-min interval) significantly enhanced alpha stability and spectral power and decreased the stability of delta activity as compared to placebo. These effects were more pronounced in the left hemisphere at rest and in the right hemisphere during mnestic activity. The perspectives of clinical application of amiridine as an antiamnestic drug are discussed in the paper.