Intracellular pH

All cells contain an intracellular fluid whose pH value is known as the intracellular pH (pHi). The pHi plays a critical role in the function of the cell, and close regulation is required for cells to survive. There are numerous mechanisms that can cause pHi to change, including metabolic acid production, leakage of acid across plasma and organelle membranes and membrane transport processes. The mechanisms that regulate pHi are usually considered to be plasma membrane transporters of which two main types exist — those independent of HCO₃⁻ and those requiring HCO₃⁻. The normal extracellular pH is 7.4±0.1.[1]

Intracellular pH is around 6.8 due to acid production. It contains low HCO₃⁻ levels and thereby at pCO₂ above 45 mmHg, the pH can not be 7.4 but much lower. The intercellular pH of HEK cells (HEK 293) is 7.3.

In the pH range between 6.8 and 7.4, lymphocytes maintain a constant internal pH of 7.17± 0.06 pH unit. Outside this range, intracellular pH changes with extracelular pH.

Pioneer researchers in the area of intracellular pH include Jacques Pouyssegur (University of Nice, France), Albrecht Schwab, University of Münster, Germany, and Diane Barber, University of California at San Francisco, USA.