The investigation of the cholinoreceptors of Limnaea stagnalis neurons with the use of bisquaternary compounds

Abstract 1. 1. The structure-activity relationships in a series of bisquaternary derivatives of terephthalic acid were studied on the small parietal ganglion neurons of Limnaea stagnalis after inhibition of cholinesterases by irreversible inhibitors. Cholinomimetic activity of the studied drugs was estimated with the use of intracellular micro-electrodes as a measure of depolarization caused by a given drug concentration. 2. 2. It was shown that the presence of ester groups in the same position as in acetylcholine (ACh) and the presence of a phenyl ring in the middle part of the molecule are important for cholinomimetic activity of bisquaternary compounds having 14–16 atoms between quaternary nitrogens. 3. 3. The increase of potency of dicholinic esters after cholinesterase inhibition was demonstrated. 4. 4. An attempt was made to use the rate of the depolarization increase for evaluation of the rate of drug-receptor interaction.