Submitted on November 26, 2002
Accepted on May 7, 2003
THE EFFECT OF CHANGES IN AMBIENT OXYGEN CONCENTRATION ON THE BIOELECTRIC PROPERTIES OF MIDDLE EAR MUCOSA
David L Mandell1*, Daniel C Devor2, Joseph V Madia3, Chia-Yee Lo3, Hilary Hake3, and Patricia A Hebda4
1 Department of Pediatric Otolaryngology, Children's Hospital of Pittsburgh, Pittsburgh, PA, USA; Department of Otolaryngology, University of Pittsburgh, Pittsburgh, PA, USA
2 Department of Cell Biology & Physiology, University of Pittsburgh, Pittsburgh, PA, USA
3 Department of Pediatric Otolaryngology, Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
4 Department of Pediatric Otolaryngology, Children's Hospital of Pittsburgh, Pittsburgh, PA, USA; Department of Otolaryngology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Cell Biology & Physiology, University of Pittsburgh, Pittsburgh, PA, USA
* To whom correspondence should be addressed. E-mail: David.Mandell{at}chp.edu.
The purpose of the present study was to directly compare the effect of 24 hours of exposure to 7% O2 (normal middle ear physiologic conditions) versus 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. While 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 when compared to 7% O2 exposure. In the presence of a calcium-dependent 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.
