FIGURE 1.

Intestinal Mg²⁺ absorption pathways Mg²⁺ absorption is mediated by two separate absorption pathways. In the small intestine, Mg²⁺ absorption is mainly of paracellular nature through tight junction complexes between adjacent epithelial cells. Here, CLDN2, −7, and − 12 enhance paracellular permeability. In the large intestine, Mg²⁺ is absorbed via active, transcellular transport facilitated by TRPM6/7 channels. Extrusion of Mg²⁺ to the blood compartment is mediated by CNNM4 on the basolateral side of the colonocytes.