Chemoattractant-induced membrane hyperpolarization in Dictyostelium discoideum. A possible role for cyclic GMP

Membrane potentials of the cellular slime mold Dictyostelium discoideum were monitored after chemotactic stimulation by measuring the distribution of the lipophilic cation tetraphenylphosphonium. Stimulation with the chemoattractant cAMP induces a transient membrane hyperpolarization which reaches its most negative value between 1-3 min after stimulation. This hyperpolarization is consistent with the opening of potassium channels. Measurements in streamer F mutant cells reveal that cGMP likely plays a role in the regulation of the cAMP-induced hyperpolarization.