Effects of local anesthetics on bacterial cells

Abstract

The membrane effects of chlorpromazine, nupercaine, tetracaine and procaine were studied using Bacillus cereus, B. megaterium, B. subtilis, and Streptococcus faecalis, protoplasts from S. faecalis, and isolated membranes from B. subtilis. Chlorpromazin, nupercaine and tetracaine produced characteristic micromorphological alterations after treatment for 5 to 30 min at pH 7.0 and 20°C; C; the membrane staining pattern changed from asymmetric to symmetric, complex mesomome-like structures appeared, and membrane fractures and solubilization occurred. Procaine at concentrations up to 100 mM did not induce detectable alterations. Protoplasts were quickly lysed by 10 mM tetracain. A rapid and extensive leakage of K+ was induced by chlorpromazin, nupercain, and tetracain. Procaine ( 100 mM) induced a slight K+ leakage. The membrane respiratory activity of intact B. cereus cells (as measured by the triphenyl tetrazolium reduction) and the succinic dehydrogenase activity of B. subtilis isolated membranes were found to be inhibited by the four local anaesthetics. The concentrations that produced 50% inhibition of those activities are correlated with the hydrophobicities of the anesthetic molecules.