Oxygen metabolites modulate sodium transport in gerbil middle ear epithelium: involvement of PGE2
Herman, P.; Tu, T.Y.; Loiseau, A.; Clerici, C.; Cassingena, R.; Grodet, A.; Friedlander, G.; Amiel, C.; Tran Ba Huy, P.
American Journal of Physiology 268(3 Pt 1): L390-L398
1995
ISSN/ISBN: 0002-9513 PMID: 7900820 Document Number: 450405
The middle ear epithelium and respiratory epithelia share basic properties such as homeostasis of air-filled cavities and mucociliary clearance toward the pharynx. With the middle ear SV40-transformed (MESV) cell line, we used the short-circuit current (I-sc) technique to investigate changes in ion transport induced by oxidants. Xanthine and xanthine oxidase on the basal side of the monolayers dramatically increased I-sc up to 50%. This effect was not affected by superoxide dismutase or mannitol, but could be blunted by catalase or 1,3-dimethyl-2-thiourea. Increasing concentrations of H-2O-2 from 10-5 to 5 times 10-4 M produced a dose-dependent increase in I-sc from 0.26 +- 0.16 up to 4.21 +- 0.43 mu-A/cm-2 (P lt 0.05, n = 5). Concentration of half-maximal stimulation (EC-50) was 4.68 times 10-5 M. This effect was inhibited by indomethacin and was related to a sodium transport, since the H-2O-2-induced increase in I-sc could be prevented or abolished by 1) apical addition of benzamil (10-6 M) and 2) substitution of sodium with N-methyl-glucamine. H-2O-2 exposure also induced indomethacin-sensitive increase in released prostaglandin (PG) E-2 (EC-50 = 5.62 times 10-5 M) and in cAMP content (EC-50 = 3.95 times 10-5 M) with similar kinetics. These results suggest that exposure of MESV cells to oxidants stimulates the production of PGE-2, which in turn increases the transepithelial sodium transport rate.