Am J Physiol Cell Physiol AJP: Lung Cellular and Molecular Physiology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Am J Physiol Cell Physiol 280: C1521-C1530, 2001;
0363-6143/01 $5.00
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Web of Science (22)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by To, C.-H.
Right arrow Articles by Candia, O. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by To, C.-H.
Right arrow Articles by Candia, O. A.
Vol. 280, Issue 6, C1521-C1530, June 2001

Model of ionic transport for bovine ciliary epithelium: effects of acetazolamide and HCO<UP><SUB>3</SUB><SUP>−</SUP></UP>

Chi-Ho To1, Chi-Wai Do1, Aldo C. Zamudio2, and Oscar A. Candia2,3

1 Laboratory of Ocular Physiology and Biochemistry, Department of Optometry and Radiography, Hong Kong Polytechnic University, Hung Hom, Hong Kong; and Departments of 2 Ophthalmology and 3 Physiology and Biophysics, Mount Sinai School of Medicine, New York, New York 10029

The possible existence of transepithelial bicarbonate transport across the isolated bovine ciliary body was investigated by employing a chamber that allows for the measurement of unidirectional, radiolabeled fluxes of CO2 + HCO<UP><SUB>3</SUB><SUP>−</SUP></UP>. No net flux of HCO<UP><SUB>3</SUB><SUP>−</SUP></UP> was detected. However, acetazolamide (0.1 mM) reduced the simultaneously measured short-circuit current (Isc). In other experiments in which 36Cl- was used, a net Cl- flux of 1.12 µeq · h-1 · cm-2 (30 µA/cm2) in the blood-to-aqueous direction was detected. Acetazolamide, as well as removal of HCO<UP><SUB>3</SUB><SUP>−</SUP></UP> from the aqueous bathing solution, inhibited the net Cl- flux and Isc. Because such removal should increase HCO<UP><SUB>3</SUB><SUP>−</SUP></UP> diffusion toward the aqueous compartment and increase the Isc, this paradoxical effect could result from cell acidification and partial closure of Cl- channels. The acetazolamide effect on Cl- fluxes can be explained by a reduction of cellular H+ and HCO<UP><SUB>3</SUB><SUP>−</SUP></UP> (generated from metabolic CO2 production), which exchange with Na+ and Cl- via Na+/H+ and Cl-/HCO<UP><SUB>3</SUB><SUP>−</SUP></UP> exchangers, contributing to the net Cl- transport. The fact that the net Cl- flux is about three times larger than the Isc is explained with a vectorial model in which there is a secretion of Na+ and K+ into the aqueous humor that partially subtracts from the net Cl- flux. These transport characteristics of the bovine ciliary epithelium suggest how acetazolamide reduces intraocular pressure in the absence of HCO<UP><SUB>3</SUB><SUP>−</SUP></UP> transport as a driving force for fluid secretion.

aqueous humor secretion; chloride fluxes; bicarbonate fluxes; Ussing chamber; short-circuit current


This article has been cited by other articles:


Home page
 IOVSHome page
C. S. Law, O. A. Candia, and C.-H. To
Inhibitions of Chloride Transport and Gap Junction Reduce Fluid Flow across the Whole Porcine Ciliary Epithelium
Invest. Ophthalmol. Vis. Sci., March 1, 2009; 50(3): 1299 - 1306.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Cell Physiol.Home page
C. W. McLaughlin, S. Zellhuber-McMillan, A. D. C. Macknight, and M. M. Civan
Electron microprobe analysis of rabbit ciliary epithelium indicates enhanced secretion posteriorly and enhanced absorption anteriorly
Am J Physiol Cell Physiol, November 1, 2007; 293(5): C1455 - C1466.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Cell Physiol.Home page
C. Y. Chan, J. A. Guggenheim, and C. H. To
Is active glucose transport present in bovine ciliary body epithelium?
Am J Physiol Cell Physiol, March 1, 2007; 292(3): C1087 - C1093.
[Abstract] [Full Text] [PDF]

Home page
 Arch OphthalmolHome page
R. Gerometta, S. M. Podos, O. A. Candia, B. Wu, L. A. Malgor, T. Mittag, and J. Danias
Steroid-Induced Ocular Hypertension in Normal Cattle
Arch Ophthalmol, October 1, 2004; 122(10): 1492 - 1497.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Cell Physiol.Home page
C.-W. Do, K. Peterson-Yantorno, C. H. Mitchell, and M. M. Civan
cAMP-activated maxi-Cl- channels in native bovine pigmented ciliary epithelial cells
Am J Physiol Cell Physiol, October 1, 2004; 287(4): C1003 - C1011.
[Abstract] [Full Text] [PDF]

Home page
 IOVSHome page
M. Shahidullah, W. S. Wilson, M. Yap, and C.-h. To
Effects of Ion Transport and Channel-Blocking Drugs on Aqueous Humor Formation in Isolated Bovine Eye
Invest. Ophthalmol. Vis. Sci., March 1, 2003; 44(3): 1185 - 1191.
[Abstract] [Full Text] [PDF]

Home page
 IOVSHome page
M. Y. Avila, R. W. Seidler, R. A. Stone, and M. M. Civan
Inhibitors of NHE-1 Na+/H+ Exchange Reduce Mouse Intraocular Pressure
Invest. Ophthalmol. Vis. Sci., June 1, 2002; 43(6): 1897 - 1902.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Cell Physiol.Home page
C. W. McLaughlin, D. Peart, R. D. Purves, D. A. Carre, K. Peterson-Yantorno, C. H. Mitchell, A. D. C. Macknight, and M. M. Civan
Timolol may inhibit aqueous humor secretion by cAMP-independent action on ciliary epithelial cells
Am J Physiol Cell Physiol, September 1, 2001; 281(3): C865 - C875.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Visit Other APS Journals Online