Cytochalasin prevents cell elongation and increases potassium efflux from embryonic lens epithelial cells: implications for the mechanism of lens fiber cell elongation.

Treatment of cultured embryonic lens epithelial cells with vitreous humor causes them to differentiate into lens fibers. Fiber differentiation is characterized by extensive cell elongation. We have previously suggested that potassium accumulation provides the driving force for the early, rapid phase of this process. Cytochalasin D prevented cell elongation, reduced potassium accumulation and increased potassium efflux from lens epithelial cells treated with vitreous humor. Potassium accumulation was also inhibited and efflux increased by the drug when lens epithelia were cultured in basal medium, in which they do not differentiate. Because vitreous humor appears to cause cell elongation by reducing potassium efflux, cytochalasin may prevent elongation by increasing potassium efflux. The results of this study suggest that the molecules that mediate potassium efflux are linked to the sub-membrane cytoskeleton.