Intracellular pH

All cells contain an intracellular fluid which has a pH value — this is known as the intracellular pH (pHi). The pHi of cells plays a critical role in their function 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–.