Active transport inhibition in rat small intestine by amphiphilic amines: an in vitro study with various local anaesthetics.

In the present investigation with rings of everted rat small intestine, amphiphilic amines such as local anaesthetics (e.g. lidocaine, procaine, tolycaine) were employed to study their effects on intestinal absorption of methyl alpha-D-glucoside, L-leucine, D-fructose, and 2-deoxy-D-glucose. All the amphiphilic amines tested, except for benzocaine, significantly inhibited Na(+)-dependent active uptake of methyl alpha-D-glucoside and L-leucine while leaving uptake of D-fructose (facilitated diffusion) and 2-deoxy-D-glucose (passive diffusion) unaffected. Increasing concentrations of lidocaine in the incubation medium inhibited the uptake of methyl alpha-D-glucoside (IC(50) approximately 3.5 mmol/L) and L-leucine (IC(50) approximately 6 mmol/L) in a dose-dependent manner. Complete reversibility of the inhibitory effect could only be achieved at short-term incubations (