Aquaporin water channel proteins in intestinal mucosa (AQP (when referring to aquaporins); no single unified abbreviation for all water transport proteins in the intestinal mucosa)

Aquaporin water channel proteins are integral membrane transporters that facilitate rapid and selective movement of water across the intestinal mucosal barrier[4][5]. In the gastrointestinal tract, several aquaporins (such as AQP1, AQP3, AQP4, AQP7, AQP8) localize to specific epithelial cells of the small intestine and colon and are essential for physiologic absorption and secretion of water, driven by osmotic gradients created by sodium and other electrolyte transporters[4][5][6]. These water channels enable the intestine to handle massive fluxes of water accompanying nutrient uptake and digestion. Dysfunction in these or in associated sodium transporters can result in diarrhea, dehydration, or other fluid balance disorders[6]. While "water transport proteins" also includes SLC family Na^+/H^+^ exchangers and epithelial sodium channels, aquaporins represent the canonical molecular family for passive water movement across the intestinal epithelium. Drugs such as tenapanor (NHE3 inhibitor) and amiloride (ENaC inhibitor) exploit these pathways therapeutically, but their manipulation poses risks of dysregulated fluid movement and systemic electrolyte imbalance[5][6].

Other names

Aquaporins (AQPs)Water channelsIntestinal water channelsIntestinal epithelial water transporters

Blockade or inhibition of water or sodium transport (e.g., tenapanor blocks NHE3, reducing Na^+^ and water absorption[6]); Inhibition of epithelial sodium channels (e.g., by amiloride, leading to water retention in the gut[5]); Inhibition of Na^+/K^+-ATPase, disrupting sodium gradient and water absorption[5].