Roles of Na+/Ca2+ exchanger 1 in digestive system physiology and pathophysiology

Figure 4 The roles of NCX1 reverse mode in the digestive system. In duodenal epithelial cells, carbachol and 5-HT can activate the reverse mode of NCX1, enhancing Ca²⁺ influx to release HCO₃^-. In hepatoma cells, NHE1 can promote H⁺ excretion and Na⁺ influx and activate the reverse mode of NCX1 to induce Ca²⁺ influx. In colon goblet cells, ATP activates the TRPM5 channel to induce Na⁺ influx, and an increase of Na⁺ concentration starts the NCX1 reverse mode and increases Ca²⁺ influx and MUC5AC expression. In pancreatic islet β cells, under glucose stimulation, NCX1 can be converted to a reverse mode to promote Ca²⁺ influx to increase insulin secretion.