Mechanism Of pH Homeostasis :

Mechanism of pH Homeostasis :

1.Proton Pumping :

These include buffering capacity of the cytoplasm and metabolic reactions that produce acids and bases.

The regulation of intracellular pH is of controlling the flow of protons across the cell membrane.

The reason for believing this is that the ΔpH (pH gradient) is dissipated or when proton ionophores are added to medium.

When the cytoplasm becomes too acidic protons are pumped out.

This is done by electroneautrally (i.e.bringing K+ into cell).

When the cytoplasm becomes too basic protons are bring it via outgoing K+ or Na+.

           pH Homeostasis Proton Pumping 

The antiporters that bring in protons in exchange for Na+ or K+ are driven by Δp, either by ΔpH.

When the inflow of protons is electrogenic

(i.e. ratio of H+/Na+ or K+).Therefore inhibition of proton pumps leads to situation where pH in = pH out.

2.Role of K+ in maintaning ΔpH :

Proton pumping to raise the intracellular pH, the excess membrane potential dissipated by inflow of cation or outflow of anions.

In neutrophilic bacteria, K+ inflow dissipates the membrane potential allowing more protons to pumped out of the cell.

This means that K+ inflow is required to raise intracellular pH.

K+ and Na+ ions play an important role in lowering the intracellular pH by bringing protons back into the cell through H+/K+ or H+/Na+ antiporters.