COMPARISON OF CYTOSOLIC LEVELS OF CALCIUM AND G-ACTIN IN DIFFUSE AND LOCALIZED ADHERENT ESCHERICHIA-COLI-INFECTED HELA-CELLS

In the present study we compared the intracellular level of free calci um ([Ca2+](i)) and monomeric (G)/total (G + F) actin ratio in Hela cel ls infected with diffuse (DAEC) and localised adherent Escherichia coi l (LAEC). The level of [Ca2+](i) was increased in both DAEC- and LAEC- infected HeLa cells. However, studies with EGTA- and dantrolene-treate d cells and also suspension of cells in Ca2+-free buffer suggested tha t the rise of [Ca2+](i) in DAEC-infected cells was due to the influx o f Ca2+ from extracellular medium, whereas Ca2+ mobilisation from the i ntracellular stores was responsible for the enhancement of [Ca2+](i) i n LAEC-infected cells. It was also evident that the infection of HeLa cells with DAEC and LAEC caused alteration of G/G + F actin ratio as c ompared to that of control cells. The ratio was much lower in LAEC-inf ected cells than that of DAEC-infected ones. Moreover, cytochalasin B inhibited both DAEC and LAEC invasion to HeLa cells, suggesting furthe r the role of microfilaments in the invasion process.