Epithelial Electrolyte Transport Physiology and the Gasotransmitter Hydrogen Sulfide

Figure 2

Epithelial ion transport responses to exogenous hydrogen sulfide in rat colon. Channels and transport mechanisms activated by H₂S in the rat colonic epithelium. Anion (Cl⁻) secretion through the cystic fibrosis transmembrane conductance regulator (CFTR) or calcium-dependent chloride channels (CaCC) is enabled after building up a cytosolic anion potential, which results from the activation of basolateral transporters notably: the Na⁺/K⁺-ATPase maintaining the K⁺ concentration gradient between the intracellular and the extracellular spaces; the Ca²⁺-dependent () and ATP-sensitive () K⁺ channels, responsible for the driving force allowing for uptake of Cl⁻ via the basolateral Na⁺-K⁺-Cl⁻ cotransporter type 1 (NKCC1). H₂S donors induce activation of the Na⁺/K⁺-ATPase and basolateral K⁺ conductance, enabling intracellular accumulation of Cl⁻, which will be secreted via the CFTR or CaCC. Also, the apical Na⁺/Ca²⁺ exchanger was activated in parallel with increase in paracellular permeability.