Effect of caffeic acid on apical transporters' dysfunction of renal proximal tubule cells under oxidative stress in vitro.

The protective effect of caffeic acid (CA) against oxidative stress-induced inhibition of proximal tubule apical transporter was investigated. In the present study, 10 -4 M H 2 O 2 did not affect cell viability regardless of incubation time. However, it decreased apical transporters' activity such as Na + /glucose cotransporter, Na + /Pi cotransporter, and Na + /H + antiporter in the proximal tubule cells. CA (>10 -6 M) prevented H 2 O 2 -induced inhibition of apical transporters. Thus, we investigated its action mechanism. CA also prevented H 2 O 2 -induced lipid peroxides formation, arachidonic acid (AA) release, and Ca 2+ uptake. In conclusion, CA, in part, prevented H 2 O 2 -induced inhibition of apical transporter activity via decrease of AA release and Ca 2+ uptake in primary cultured renal proximal tubule cells.