CHLORIDE CHANNELS
Chloride channels are ubiquitous proteins found in every cell from bacteria to human. Their functions include cell volume and pH regulation, stabilization of the membrane potential, signal transduction, transepithelial transport and acidification of intracellular organelles. Regulation of Cl- channels is carried out by various intracellular messengers (such as calcium and cAMP), pH, extracellular ligands and membrane voltage. The main family of chloride channels, CLC chloride channels, includes both voltage-gated and cAMP-activated channels.

A defect in the cAMP activated channel CFTR, causes decreased fluid secretion and defective chloride conductance in the epithelia which leads to cystic fibrosis (CF). Consequently the pH of intracellular organelles is more alkaline in CF cells. CLC-2, one of the voltage-gated Cl- channels, plays an important role in the stabilization of the transmembrane anionic concentration gradient in neurons. Thus, CLC2 influences the effect of GABA-A receptor activation and regulates neuronal excitability.