through phospholipase C (PLC)–protein kinase C (PKC)
signaling pathway to activate the epithelial Na?/H?
exchanger (NHE) and H?-ATPase activity [15, 17].
ASIC1a is activated by extracellular pH below 6.9 with
pH0.5 of 6.2–6.8 [13], whereas TRPV4 requires a more
acidic pH for activation (pH[6.0) and is fully activated at
pH 4.0 [18]. Both ASIC1a and TRPV4 are Ca2? channels
that trigger Ca2? signaling to regulate epithelial HCO3
-
secretion [11, 19]. Activation of TRPV4 also modulates
paracellular permeability and Cldn expressions by a Ca2?-
dependent mechanism [20]. It is not known whether
intestinal acid sensing ASIC1a, OGR1, and TRPV4 have
any role in apical acidity-induced stimulation of paracellular
passive Mg2? absorption. The present study investigated
the role of intestinal acid sensors in the regulation of
paracellular passive Mg2? absorption. The results showed
that OGR1 enhanced whereas ASIC1a decreased the passive
intestinal Mg2? absorption