ATP and the autonomy of the contractile vacuole in Amoeba proteus.

Contractile vacuole function in amoebae treated with immobilizing (5 mM) and nonimmobilizing (0.125 mM) concentrations of ATP has been studied. In ATP-immobilized amoebae, most vacuolar parameters are accelerated, especially the rate of output which passes from 30 to 70 micron3/sec. This favors the concept of an autonomous vacuole, fully functional in the absence of any bulk contribution to it from remote points of the cell. A lower concentration of ATP (0.125 mM), which does not inhibit movement, causes a still greater acceleration of vacuolar function. Work is in progress to elucidate the site and mode of action of exogenous ATP on Amoeba.