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Monday 01 September 2003

The effect of changes in ambient oxygen concentration on the bioelectric properties of middle ear mucosa.

By: Mandell DL, Devor DC, Madia JV, Lo CY, Hake H, Hebda PA.

Am J Physiol Cell Physiol 2003 Sep;285(3):C618-22

The purpose of the present study was to compare the effect of 24 h of exposure to 7% O2 (normal middle ear physiological conditions) vs. 21% O2 (found in the middle ear after ventilation tube placement) on transepithelial Na+ absorption and Cl- secretion in cultured gerbil middle ear epithelial cell monolayers. Although no difference in apical Na+ absorption was identified, the UTP-induced stimulation of apical Cl- secretion in the presence of apical Na+ channel blockade with amiloride was significantly enhanced after exposure to 21% O2 compared with 7% O2 exposure. In the presence of a calcium-activated Cl- channel inhibitor, DIDS, UTP-induced stimulation of Cl- secretion after 21% O2 exposure was decreased, suggesting a role for calcium-activated Cl- channels in middle ear Cl- secretion in response to relative hyperoxia.

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