Action of a cytotoxin from Pseudomonas aeruginosaon human leukemic cell lines : Increase in cell permeability to Ca 2+ and Mn 2+ and lack of stimulation of inositol lipid turnover

Abstract

Quin2 loaded human leukemic, JURKAT and K562 cells, were exposed to various doses of Pseudomonas aeruginosa cytotoxin. This cytotoxin induced an increase in quin2 fluorescence indicating an increase in the cytoplasmic free Ca 2+ concentration. The rate of the fluorescence increase and the lag time before the response were dependent on the doses of the cytotoxin. Addition of MnCl 2 to the cytotoxin-treated cells induced a decrease in the quin2 fluorescence at rates dependent on the doses of the cytotoxin. The cytotoxin did not stimulate the inositol lipid turnover in JURKAT cells, which was determined by the accumulation of [ 3H]inositol phosphates in myo-[2- 3H]inositol-prelabeled cells in the presence of LiCl. These results indicate that the cytotoxin increases cell permeability to both Ca 2+ and Mn 2+ by direct breakdown of the permeability barrier of the plasma membrane.