Acid-sensitive ion channels in gastrointestinal function.
Deviations from the physiological values of extracellular pH are monitored by multiple acid sensors. Acid-sensing ion channels are activated by moderate acidification, whereas transient receptor potential cation channels, notably TRPV1, are gated by severe acidosis. In contrast, ionotropic purinoceptor (P2X) ion channels, particularly P2X(2), and two-pore domain background K(+) channels, such as TASK, do not directly signal acidification but rather modulate cell membrane excitability in response to acidosis. These acid sensors, which are expressed by afferent neurons, are most relevant to the regulation of acid secretion, foregut motility and mucosal protection, as well as to gastrointestinal disturbances associated with inflammation, ischaemia and stasis.
Holzer
Peter
P
Department of Experimental and Clinical Pharmacology, University of Graz, Universitätsplatz 4, A-8010 Graz, Austria. peter.holzer@uni-graz.at
D015746:Abdominal Pain / Q000503:physiopathology; D000143:Acids / Q000378:metabolism*; D000818:Animals; D027682:Cation Transport Proteins / Q000502:physiology; D004068:Digestive System Physiological Phenomena; D015640:Ion Channel Gating / Q000502:physiology*; D007473:Ion Channels / Q000378:metabolism* / Q000502:physiology; D011955:Receptors, Drug / Q000502:physiology; D011983:Receptors, Purinergic / Q000502:physiology; D050916:TRPV Cation Channels; D017833:Visceral Afferents / Q000502:physiology
D000143:Acids; D027682:Cation Transport Proteins; D007473:Ion Channels; D011955:Receptors, Drug; D011983:Receptors, Purinergic; D050916:TRPV Cation Channels; C416986:TRPV4 protein, human