Benzylamine-related compounds stimulate rat vas deferens neurotransmission and potentiate memory in the mouse acting as potassium channel blockers

In stimulated rat vas deferens, the new compound 2,6-dibutylbenzylamine (B25) and some related benzylamines, first potentiated then completely inhibited electrically-induced twitch response, showing the biphasic effect previously observed in unstimulated preparations. To verify if this effect could be referred to as a modulation of potassium channels the activity of some benzylamines, KCl, tetraetylammonium (TEA), BaCl2, 4-aminopyridine (4-AP), glibenclamide (GLI), charibdotoxin (ChTX) and apamin (APA) has been compared. While KCI and benzylamine-related derivatives induced biphasic effects, TEA, 4-AP, BaCl2, GLI stimulated but were unable to inhibit the twitches. The pretreatment with stimulating concentrations of TEA, 4-AP, GLI, APA or ChTX and B25, as reference compound in the benzylamine series, dose-dependently reduced the stimulatory effect of KCl but were unable to modify the inhibitory effect induced by this ion. Both KCl and B25 potentiated each others own inhibitory effect suggesting that, unlike other potassium channel blockers, they could modulate in an opposite way voltage-dependent potassium channels in order to facilitate and then depress neurotransmission. In other experiments, benzylamines, KCl, TEA, 4-AP and GLI reverted the inhibitory effect of cromakalim and omega-conotoxin GVIA (omega-CTX). This effect further supports a common mechanism of action (potassium channel blockade) probably inducing the opening of Ca2+ channels different from N or L in the preparation. Finally, the prevention of minoxidil-induced amnesia in the mouse by B25 and related benzylamines, comparable to the same effect shown by TEA and 4-AP, indicates that these compounds are endowed with potential pharmacological activity in the CNS as well. (C) 2000 Academic Press.