Omeprazole decreases magnesium transport across Caco-2 monolayers

AIM:To elucidate the effect and underlying mechanisms of omeprazole action on Mg 2+ transport across the intestinal epithelium.METHODS:Caco-2 monolayers were cultured in various dose omeprazole-containing media for 14 or 21 d before being inserted into a modified Ussing chamber apparatus to investigate the bi-directional Mg 2+ transport and electrical parameters.Paracellular permeability of the monolayer was also observed by the dilution potential technique and a cation permeability study.An Arrhenius plot was performed to elucidate the activation energy of passive Mg 2+ transport across the Caco-2 monolayers.RESULTS:Both apical to basolateral and basolateral to apical passive Mg 2+ fluxes of omeprazole-treated epithelium were decreased in a dose-and time-dependent manner.Omeprazole also decreased the paracellular cation selectivity and changed the paracellular selective permeability profile of Caco-2 epithelium to Li +,Na +,K +,Rb +,and Cs + from seriesⅦto seriesⅥof the Eisenman sequence.The Arrhenius plot revealed the higher activation energy for passive Mg 2+ transport in omeprazoletreated epithelium than that of control epithelium,indicating that omeprazole affected the paracellular channel of Caco-2 epithelium in such a way that Mg 2+ movement was impeded.CONCLUSION:Omeprazole decreased paracellular cation permeability and increased the activation energy for passive Mg 2+ transport of Caco-2 monolayers that led to the suppression of passive Mg 2+ absorption.