HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Do, C.-W. Articles by To, C.-H. Search for Related Content PubMed PubMed Citation Articles by Do, C.-W. Articles by To, C.-H.

Chloride Secretion by Bovine Ciliary Epithelium: a Model of Aqueous Humor Formation

From the Laboratory of Ocular Physiology and Biochemistry, Department of Optometry and Radiography, The Hong Kong Polytechnic University, Hung Hom, Hong Kong.

PURPOSE. To study the physiological mechanisms of the Cl transport across the bovine ciliary body-epithelium (CBE).

METHODS. Fresh isolated bovine CBE was mounted in an Ussing-type chamber. The effects of ion substitution and transport inhibitors on electrical measurements and Cl transport were investigated.

RESULTS. The potential difference (PD) across the preparation was 0.55 ± 0.04 mV and was consistently negative at the aqueous side. The short-circuit current (SCC) and tissue resistance (R_t) were found to be 8.0 ± 0.7 µA/cm² and 72 ± 3 /cm², respectively. Both the PD and the SCC of the bovine CBE were found to depend primarily on the concentration of the Cl bath and to a lesser extent on the Na or HCO₃ concentration. At 30 mM Cl, the polarity of the PD and the direction of the SCC were reversed. Reducing the extracellular Na or Cl concentration abolished the net Cl transport into the eye under the short-circuited condition. Bilateral bumetanide (0.1 mM), but not 4,4'-diisothiocyanatostilbene-2-2'-disulfonic acid (DIDS; 0.1 mM), greatly inhibited the Cl transport. Bumetanide, when applied to either side, inhibited the Cl transport. The effect, however, was three times greater on the stromal side than on the aqueous surface. Bilateral heptanol (3.5 mM) and 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB; 0.1 mM) on the aqueous side also inhibited the Cl transport by 80% and 92%, respectively.

CONCLUSIONS. The results suggest that the major Cl influx pathway at the basolateral border in pigmented epithelial cells is through the Na-K-2Cl cotransporter, but not the Cl/HCO₃ and Na/H double exchangers. Intercellular gap junctions between the two cell layers and the NPPB-sensitive Cl channels at the basolateral surface in nonpigmented epithelial cells also play a crucial role in regulating the Cl movement across the functional syncytium.

This article has been cited by other articles:

				S. Selvam, P. B. Thomas, H. J. Gukasyan, A. S. Yu, D. Stevenson, M. D. Trousdale, A. K. Mircheff, J. E. Schechter, R. E. Smith, and S. C. Yiu Transepithelial bioelectrical properties of rabbit acinar cell monolayers on polyester membrane scaffolds Am J Physiol Cell Physiol, October 1, 2007; 293(4): C1412 - C1419. [Abstract] [Full Text] [PDF]

				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]

				O. A. Candia, C.-H. To, and C. S. Law Fluid Transport across the Isolated Porcine Ciliary Epithelium Invest. Ophthalmol. Vis. Sci., January 1, 2007; 48(1): 321 - 327. [Abstract] [Full Text] [PDF]

				C.-W. Kong, K.-K. Li, and C.-H. To Chloride Secretion by Porcine Ciliary Epithelium: New Insight into Species Similarities and Differences in Aqueous Humor Formation Invest. Ophthalmol. Vis. Sci., December 1, 2006; 47(12): 5428 - 5436. [Abstract] [Full Text] [PDF]

				M. R. Calera, H. L. Topley, Y. Liao, B. R. Duling, D. L. Paul, and D. A. Goodenough Connexin43 is required for production of the aqueous humor in the murine eye J. Cell Sci., November 1, 2006; 119(21): 4510 - 4519. [Abstract] [Full Text] [PDF]

				C. W. Do, K. Peterson-Yantorno, and M. M. Civan Swelling-activated cl- channels support cl- secretion by bovine ciliary epithelium. Invest. Ophthalmol. Vis. Sci., June 1, 2006; 47(6): 2576 - 2582. [Abstract] [Full Text] [PDF]

				O. A. Candia, C.-H. To, R. M. Gerometta, and A. C. Zamudio Spontaneous Fluid Transport across Isolated Rabbit and Bovine Ciliary Body Preparations Invest. Ophthalmol. Vis. Sci., March 1, 2005; 46(3): 939 - 947. [Abstract] [Full Text] [PDF]

				C. W. Do, W. Lu, C. H. Mitchell, and M. M. Civan Inhibition of Swelling-Activated Cl- Currents by Functional Anti-ClC-3 Antibody in Native Bovine Non-Pigmented Ciliary Epithelial Cells Invest. Ophthalmol. Vis. Sci., March 1, 2005; 46(3): 948 - 955. [Abstract] [Full Text] [PDF]

				C.-W. Do, C.-W. Kong, and C.-H. To cAMP Inhibits Transepithelial Chloride Secretion across Bovine Ciliary Body/Epithelium Invest. Ophthalmol. Vis. Sci., October 1, 2004; 45(10): 3638 - 3643. [Abstract] [Full Text] [PDF]

				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]

				R. Wu, K. Yao, J. Flammer, and I. O. Haefliger Role of Anions in Nitric Oxide-Induced Short-Circuit Current Increase in Isolated Porcine Ciliary Processes Invest. Ophthalmol. Vis. Sci., September 1, 2004; 45(9): 3213 - 3222. [Abstract] [Full Text] [PDF]

				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]

				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]

				D. Z. Ellis, J. A. Nathanson, J. Rabe, and K. J. Sweadner Carbachol and Nitric Oxide Inhibition of Na,K-ATPase Activity in Bovine Ciliary Processes Invest. Ophthalmol. Vis. Sci., October 1, 2001; 42(11): 2625 - 2631. [Abstract] [Full Text] [PDF]

				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]

				C.-H. To, C.-W. Do, A. C. Zamudio, and O. A. Candia Model of ionic transport for bovine ciliary epithelium: effects of acetazolamide and HCO3- Am J Physiol Cell Physiol, June 1, 2001; 280(6): C1521 - C1530. [Abstract] [Full Text] [PDF]

				R. K. Wetzel and K. J. Sweadner Immunocytochemical Localization of NaK-ATPase Isoforms in the Rat and Mouse Ocular Ciliary Epithelium Invest. Ophthalmol. Vis. Sci., March 1, 2001; 42(3): 763 - 769. [Abstract] [Full Text]