Studies on streaming. I. Inhibition of protoplasmic streaming and cytokinesis of Chaos chaos by adenosine triphosphate and reversal by magnesium and calcium ions

In Chaos chaos streaming, motility, and cytokinesis were inhibited nearly 100% for several hours by 2.5–5 mM sodium adenosine triphosphate (ATP)¹ added to culture fluid. All three effects were completely prevented by the addition of equimolar Mg⁺⁺ or Ca⁺⁺ ions but not Na⁺ to the ATP/culture fluid solution. The effects of ATP were not reproduced by EDTA, EGTA, colchicine, or AMP. Sodium pyrophosphate produced about 50% inhibition at 5 mM. Studies with ¹⁴C-ATP showed that 5 x 10^-5 to 5 x 10^-4 mmole of ATP was firmly associated with each milliliter of packed cells after an hour''s incubation at 24°C. Labeling studies also showed that prevention of the ATP effects by Mg⁺⁺ ions was not due to a decrease in the amount of ATP associated with the cells.