Cyclic AMP induces a transient alkalinization in Dictyostelium

Abstract

In a wide range of cell types, stimulus-response coupling is accompanied by a rise in cytoplasmic pH (pH i). It is shown that stimulation of developing Dictyostelium discoideum cells with the chemoattractant cAMP also results in a rise in pH i. About 1.5 min after stimulation, pH i starts increasing from pH i∼7.45 to pH i∼7.60, as is revealed independently by two different pH null-point methods. The rise in pH i is transient, also with a persistent stimulus, and effectively inhibited by diethylstilbestrol (DES), strongly suggesting that the rise in pH i is accomplished by the DES-sensitive plasma membrane proton pump which has been demonstrated in D. discoideum.