AJP - Lung Cellular and Molecular Physiology, Vol 268, Issue 3 390-L398, Copyright © 1995 by American Physiological Society
Oxygen metabolites modulate sodium transport in gerbil middle ear epithelium: involvement of PGE2
P. Herman, T. Y. Tu, A. Loiseau, C. Clerici, R. Cassingena, A. Grodet, G. Friedlander, C. Amiel and P. Tran Ba Huy
Laboratoire d'Otologie Experimentale, Faculte Lariboisiere-Saint-Louis, Paris.
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 (Isc) technique to investigate changes in ion
transport induced by oxidants. Xanthine and xanthine oxidase on the basal
side of the monolayers dramatically increased Isc 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 H2O2
from 10(-5) to 5 x 10(-4) M produced a dose-dependent increase in Isc from
0.26 +/- 0.16 up to 4.21 +/- 0.43 microA/cm2 (P < 0.05, n = 5).
Concentration of half-maximal stimulation (EC50) was 4.68 x 10(-5) M. This
effect was inhibited by indomethacin and was related to a sodium transport,
since the H2O2-induced increase in Isc could be prevented or abolished by
1) apical addition of benzamil (10(-6)M) and 2) substitution of sodium with
N-methyl-glucamine. H2O2 exposure also induced indomethacin-sensitive
increase in released prostaglandin (PG) E2 (EC50 = 5.62 x 10(-5) M) and in
cAMP content (EC50 = 3.95 x 10(-5) M) with similar kinetics. These results
suggest that exposure of MESV cells to oxidants stimulates the production
of PGE2, which in turn increases the transepithelial sodium transport rate.
