Dimethylsulfoxide potentiates the suppressive effects of lidocaine on synaptic transmission in bullfrog sympathetic ganglion.
The effects of dimethylsulfoxide used as a solvent on the suppressive effects of lidocaine on synaptic transmission were examined in the bullfrog sympathetic ganglion. Compound action potentials (CAP) in response to orthodromic stimulation of the presynaptic nerve trunk were recorded extracellularly from the bullfrog sympathetic ganglion. Application of lidocaine dissolved in normal Ringer's solution significantly decreased the amplitude of CAP. This suppressive effect of lidocaine was markedly potentiated when lidocaine was dissolved in 0.1% DMSO solution. A similar potentiating effect of DMSO was observed on the suppressive action of lidocaine on acetylcholine (ACh)-induced depolarizing response recorded intracellularly from the sympathetic ganglion cell. On the other hand, 0.1% DMSO solution alone had no effect on synaptic transmission, resting membrane potential, resting membrane resistance or ACh receptor activity. The present findings suggest that DMSO as solvent should be used carefully because of its potentiating effect on drug actions. Since the effect of lidocaine is due to the suppression of nicotinic ACh receptor at the postsynaptic membrane, DMSO may allosterically act on the nicotinic ACh receptor causing an increase in efficacy of lidocaine.
Somei
K
K
Department of Oral Physiology, Iwate Medical University School of Dentistry, Morioka, Japan.
Mizuma
K
K
Nara
K
K
Matsuya
H
H
Yoda
J
J
Sasaki
K
K
Kashimoto
T
T
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D004121:Dimethyl Sulfoxide / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005728:Ganglia, Sympathetic / Q000187:drug effects*; D008012:Lidocaine / Q000494:pharmacology*; D011892:Rana catesbeiana; D009435:Synaptic Transmission / Q000187:drug effects*
D008012:Lidocaine; D000109:Acetylcholine; D004121:Dimethyl Sulfoxide