Comparative study on effects of cytochalasins B and D on F-actin content in different cell lines and different culture conditions.

Effects of cytochalasins on actin polymerization state in living cells were measured using fluorimetry of TRITC-phalloidin bound to F-actin. Normal (3T3) and tumour (SV-3T3, B16 melanoma, and Ehrlich ascites) cells were treated with cytochalasin B and cytochalasin D (1 microgram/ml). Three effects of cytochalasins were demonstrated--depolymerization of F-actin, promotion of polymerization, and redistribution of actin without change in polymerization state. Occurrence of a given effect was dependent on cell type, cell density, cytochalasin concentration and type. This indicates that cells from different lines, and even the same cells in different culture conditions may differ significantly in their state of actin polymerization, which we suppose is the cause of their different reactions to cytochalasins. Accordingly, caution should be taken in generalizing the results concerning the effect of cytochalasis on the polymerization state of actin.