Cyclic AMP induces a transient alkalinization in Dictyostelium

Area of Science:

• Cell Biology
• Biochemistry

Background:

• Stimulus-response coupling in cells often involves changes in cytoplasmic pH (pHi).
• Dictyostelium discoideum cells are a model organism for studying cellular responses to chemical signals.

Purpose of the Study:

• To investigate the effect of the chemoattractant cAMP on cytoplasmic pH (pHi) in Dictyostelium discoideum.
• To identify the mechanism responsible for cAMP-induced pHi changes.

Main Methods:

• Utilized two distinct pH null-point methods to measure intracellular pH.
• Stimulated Dictyostelium discoideum cells with cAMP and monitored pHi over time.
• Assessed the effect of diethylstilbestrol (DES) on the observed pHi changes.

Main Results:

• cAMP stimulation led to a transient increase in pHi from approximately 7.45 to 7.60 in Dictyostelium discoideum cells.
• The pHi rise occurred about 1.5 minutes after stimulation and persisted even with continuous stimulation.
• Diethylstilbestrol (DES) significantly inhibited the cAMP-induced pHi elevation.

Conclusions:

• The chemoattractant cAMP induces a measurable rise in cytoplasmic pH in Dictyostelium discoideum.
• The DES-sensitive plasma membrane proton pump is likely responsible for mediating the observed pHi increase.
• This finding contributes to understanding stimulus-response coupling mechanisms in eukaryotic cells.