[Effect of ethymisole on long-term memory]. / O vliianii étimizola na dolgovremennuiu pamiat'.

Influence of ethymisol (bismethylamid of 1-ethylimidasol-4,5-dicarbonic acid) on learning and retention of habit was studied in experiments on rats by the method of active conditioned avoidance of electrical stimulation. At the same time optimal conformation form of the drug was determined by the method of proton magnetic resonance and by means of infrared spectra and theoretical conformation analysis. A single administration of ethymisol in the dose of 3 mg/kg reduced the deficit of the avoidance habit, when tested in 30 and 60 days following learning. A stable conformation of the ethymisol molecule with a planar arrangement of atoms of its heterocycle and amide groups was found in which the interaction of this substance with biological macromolecules was most active. The ethymisol effect on the long-term memory apparently results from a stable facilitation of synaptic transmission based on stabilization of spatial structure of biological macromolecules in the given conformation.

[H1- and H2-receptor sensitivity to 3-(beta-aminoethyl)-1,2,4-triazole derivatives]. / Chuvstvitel'nost' H1- i H2-retseptorov gistamina k proizvodnym 3-(beta-minoetil)-1,2,4-triazola.

Histamine-like derivatives of 3-(beta-aminoethyl)-1,2,4-trizole were synthetized and subjected to a pharmacological study. The sensitivity of H1- and H2-receptors to these substances was defined by the following tests, viz. in the isolated uterus of a rat, on the isolated atrium of a guinea pig and measurements of the blood pressure nn a cat. The derivative 3-(beta-aminoethyl)-5-amino-1,2,4-triazole (IEM-813) affects predominantly H1-receptors, while 3-(aminoethyl)-5-amino-1,2,4,triazole (IEM-759) has the closest affinity for H2-receptors, The authors presume that corresponding zones of histamine recpetors differ in their lyophilic and hydrophilic properties.

[Occurrence of atypical histamine H2 receptors in the wall of the frog subclavian vein]. / O sushchestvovanii atipichnykh H2-gistaminovykh retseptorov v stenke podkliuchichnoi veny liagushki.

Selective H2-histamine agonist dimaprit was shown to produce relaxation of the isolated frog subclavian vein, with it persisting under the effect of selective H2-histamine antagonist cimetidine. Possible nonspecific mechanisms of relaxation produced by histamine are discussed. The data presented do not exclude that there are atypical H2-histamine receptors in subclavian vein of frogs, the activation of which initiates the attenuation of the active tension.