Omeprazole is a common therapeutic tool for acidpeptic
disorders. Its active sulphenamide form selectively
and covalently interacts with the H+/K+-ATPase, particularly
the extracellular cysteine 813, leading to potent inhibition
of H+/K+-ATPase activity[9]. Previous reports demonstrated
that prolonged omeprazole administration led
to hypomagnesemia and hypomagnesuria in humans[10,11].
Withdrawal of omeprazole and intravenous Mg2+ replacement,
but not high dose oral Mg2+ supplement, could normalize
the plasma and urinary Mg2+ levels[10,12]. Renal Mg2+
handling was normal in patients with severe hypomagnesemia
associated with long-term use of omeprazole[12-14].
This body of evidence suggested an inhibitory effect of
omeprazole on intestinal Mg2+ absorption. However, the
direct action of omeprazole on intestinal Mg2+ transport
is still elusive. The present study, therefore, aimed to elucidate
the effect of omeprazole as well as obtain information
regarding possible mechanisms of omeprazole action
on Mg2+ transport across the intestinal epithelium. This
study employed a monolayer of Caco-2 cells which is a
suitable in vitro model for studying intestinal transport of
divalent cations, e.g. Ca2+[15] and Mg2+[1