Bikarbonatkanal

Bikarbonatkanal refers to the collection of membrane pathways that move bicarbonate ions (HCO3−) across cell membranes. Bicarbonate transport is a central part of maintaining acid–base homeostasis, regulating intracellular pH, CO2 transport, and the secretion of digestive fluids in several organs.

There are two main categories of pathways: channels and transporters. Bicarbonate movement can occur through channels such as CFTR, which conducts bicarbonate in addition to chloride and is regulated by cellular signaling. In addition, bicarbonate transport is mediated by a range of transport proteins that couple bicarbonate movement to other ions. The sodium-bicarbonate cotransporters (NBC family) reabsorb or secrete bicarbonate in a sodium-dependent manner, while anion exchangers (such as members of the AE/SLC4 and SLC26 families) exchange chloride for bicarbonate in a sodium-independent manner.

Bicarbonate transport is especially important in the kidney for reclaiming filtered bicarbonate and maintaining systemic pH, in the pancreas and gastrointestinal tract for alkaline secretions, in the airways where bicarbonate contributes to the surface liquid pH, and in red blood cells where bicarbonate participates in CO2 transport. Regulation of these pathways integrates metabolic state, respiration, and hormonal signals.

Clinical relevance includes disorders of acid–base balance that arise from impaired bicarbonate transport, cystic fibrosis-related changes in bicarbonate secretion, and various renal tubular disorders. The term “bikarbonatkanal” is used in physiology to describe the functional pathways of bicarbonate movement rather than a single protein.