Acid sensing ion channels
A family of proteins combined to form acid sensing ion channels (ASIC) of the degenerin family. The channels are gated by acidity (threshold pH 6.8), and are often found in nociceptive afferents. There are several subtypes of ASICs including ASIC1, ASIC2, ASIC3 and ASIC4. ASICs are expressed throughout the central and peripheral nervous system. Asic channels are related to epithelial sodium channels in the kidney (ENaC), and to degenerins in the model organism C. elegans. ASIC channels may play a role in mediating cardiac ischemic pain by sensing extracellular acidification. Mice and C. elegans worms, deficient in ASIC subunits, show deficits in mechanosensation.