EFFECTS OF TRICLOSAN ON THE RAT PHRENIC NERVE-DIAPHRAGM PREPARATION

It has been reported that the lipid soluble, anti-inflammatory drug tr iclosan, which is currently used in toothpastes and mouthrinses, may r educe pain. This may be an aspect of the anti-inflammatory effect of t riclosan, which probably reduces the production of prostaglandin PGE(2 ). However, triclosan may also exhibit a direct analgesic effect throu gh an effect on excitable membranes. The aim of the present study was to examine the possible effect of triclosan on the nerve action potent ial, on the neuromuscular transmission and on the excitation-contracti on coupling of skeletal muscle. Phrenic nerve-hemidiaphragm preparatio ns, as well as isolated phrenic nerves, were dissected from Wistar alb ino rats and mounted by standard methods in Tyrode solution. Both duri ng indirect and direct stimulation, the preparations were irreversibly inhibited by triclosan at concentrations higher than 5.0x10(-6) M. At low concentrations, the inhibition of the twitches during indirect st imulation and of the compound action potential was probably caused by a threshold increase for excitation of the phrenic nerve. At high conc entrations, an additional inhibitory effect at the neuromuscular junct ion was disclosed. The directly stimulated preparation was also probab ly inhibited by an increase of the threshold for initiation of the mus cle action potentials. In addition, a reduced KCl contracture and an a cceleration of the caffeine contracture indicated an interaction with the sarcolemma. These results suggest that the analgesic effect of tri closan may be due to a direct interaction with excitable membranes.