Effect of exogenous ATP on the volume of TA₃ ascites tumor cells

When exogenous ATP is added to suspensions of TA 3 ascites tumor cells suspended in Ca ++ and Mg ++ free media, a significant increase in cell volume can be measured. This increase is reversible upon addition of Ca ++ and/or Mg ++ back to the media. The enlargement of these cells is temperature sensitive and specific for ATP; no other nucleotides, EDTA or ouabain were effective. The evidence suggest that this phenomena may be due to an alteration in membrane permeability and that the regulation of membrane permeability is an energy dependent process.