Intracellular pH transients induced by Co2 or NH3

Area of Science:

• Cellular physiology
• Biophysics
• Acid-base balance

Background:

• Intracellular pH (pHi) regulation is crucial for cellular function.
• Exposure to gases like CO2 and NH3 can significantly alter pHi.
• Previous studies have observed transient pHi shifts but lacked comprehensive models.

Purpose of the Study:

• To analyze experimental data on pHi transients induced by CO2 and NH3.
• To develop and validate a physiochemical model explaining observed pHi dynamics.
• To differentiate between passive and active transport mechanisms influencing pHi.

Main Methods:

• Review of experimental studies involving CO2 and NH3 exposure.
• Development of a quantitative physiochemical model for pHi changes.
• Comparison of model predictions with experimental data for NH3 and CO2 transients.

Main Results:

• Observed pHi acidification (CO2) and alkalinization (NH3) followed by return to baseline.
• Demonstrated rebound effects (more alkaline or acid) upon removal of test solutions.
• Model successfully explains both transient and rebound phenomena, distinguishing passive (NH3) and active (CO2) transport.

Conclusions:

• A unified physiochemical model explains CO2 and NH3-induced pHi transients and rebounds.
• CO2-induced pHi changes necessitate postulating an active proton pump.
• NH3-induced pHi changes can be explained by passive diffusion alone.
• The findings have implications for understanding physiological responses to CO2 and NH3 exposure.