Epithelial chloride secretory pathway

The epithelial chloride secretory pathway is a fundamental physiological process that regulates the transport of chloride ions across epithelial tissues, thereby driving the osmotic movement of water (nih.gov, 2013). This pathway is critical for maintaining the hydration and pH of mucosal surfaces in organs such as the lungs, intestines, and pancreas (nih.gov, 2013). The process involves a coordinated sequence of events: chloride enters the cell at the basolateral membrane via the Na+-K+-2Cl- cotransporter (NKCC1), powered by the Na+/K+-ATPase pump, and exits at the apical membrane through specialized channels, most notably the cystic fibrosis transmembrane conductance regulator (CFTR) and calcium-activated chloride channels (CaCCs) like TMEM16A (nih.gov, 2013; researchgate.net, 2013). Dysregulation of this pathway is central to various pathologies; for example, deficient chloride secretion due to CFTR mutations causes cystic fibrosis, while excessive secretion triggered by bacterial enterotoxins leads to life-threatening secretory diarrhea (nih.gov, 2013; unc.edu, 1991). Therapeutic interventions target various components of this pathway, including CFTR modulators for cystic fibrosis, chloride channel activators like lubiprostone for constipation, and inhibitors like crofelemer for diarrhea management (nih.gov, 2013; unc.edu, 1992).

Other names

Epithelial chloride secretionIntestinal chloride secretory pathwayAirway chloride secretory pathwayChloride secretory pathway

Activation or inhibition of apical chloride channels (CFTR, CaCC), activation of ClC-2 channels, inhibition of basolateral transporters (NKCC1), and modulation of upstream regulatory receptors such as GC-C and P2Y2.