|
|
||||||||
School of Molecular and Medical Biosciences, University of Wales, Cardiff CF1 3US, United Kingdom
The ciliary epithelium of the eye secretes the aqueous humor. It
is a double epithelium arranged so that the apical surfaces of the
nonpigmented ciliary epithelial (NPCE) and pigmented ciliary epithelial
(PCE) cells face each other and the basolateral membranes face the
inside of the eye and the blood, respectively. We have investigated the
volume responses of both single cells and coupled pairs from this
tissue to osmotic challenge. Both NPCE and PCE cells undergo regulatory
volume increase (RVI) and decrease (RVD) when exposed to hyper- and
hyposmotic solution, respectively. In hyposmotic solution single cells
swell and return to their original volumes within ~3 min. In
nonpigmented cells RVD could be inhibited by blockers of
volume-activated Cl
channels [tamoxifen (100%) > quinidine (87%) > DIDS (84%) > 5-nitro-2-(3-phenylpropylamino)benzoic acid (80%) > SITS
(58%)] and K+ channels
[Ba2+
(31%)]. However, in PCE cells these inhibitors and
additionally tetraethylammonium and
Gd3+ were without effect. Only
bumetanide, an inhibitor of
Na+-K+-2Cl
cotransport, was found to have any effect on RVD in PCE cells. NPCE-PCE
cell coupled pairs also underwent RVD, but with altered kinetics. The
onset of RVD of the PCE cell in a pair occurred
80 s before that of
the NPCE cell, and the peak swell was reduced. This is consistent with
fluid movement from the PCE to the NPCE cell. The effect of the
volume-activated Cl
channel
inhibitor tamoxifen was to eliminate this difference in the times of
onset of RVD in coupled cell pairs and to inhibit RVD in both the NPCE
and PCE cells partially. On the basis of these observations we suggest
that fluid is transferred from the PCE to the NPCE cell in coupled
pairs during cell swelling and the subsequent RVD. Furthermore, we
speculate that reciprocal RVI-RVD could underlie aqueous humor secretion.
ciliary epithelium; secretion; fluid transport; volume regulation; ion channels
This article has been cited by other articles:
![]() |
L. Chen, L. Wang, L. Zhu, S. Nie, J. Zhang, P. Zhong, B. Cai, H. Luo, and T. J. C. Jacob Cell cycle-dependent expression of volume-activated chloride currents in nasopharyngeal carcinoma cells Am J Physiol Cell Physiol, October 1, 2002; 283(4): C1313 - C1323. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. H. Mitchell, J. C. Fleischhauer, W. D. Stamer, K. Peterson-Yantorno, and M. M. Civan Human trabecular meshwork cell volume regulation Am J Physiol Cell Physiol, July 1, 2002; 283(1): C315 - C326. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. V. Patil, Z. Han, M. Yiming, J. Yang, P. Iserovich, M. B. Wax, and J. Fischbarg Fluid transport by human nonpigmented ciliary epithelial layers in culture: a homeostatic role for aquaporin-1 Am J Physiol Cell Physiol, October 1, 2001; 281(4): C1139 - C1145. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. V. Fisher, A. Telser, J. E. Phillips, and D. B. Yeates Regulation of vocal fold transepithelial water fluxes J Appl Physiol, September 1, 2001; 91(3): 1401 - 1411. [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] |
||||
![]() |
D. A. Carre, C. H. Mitchell, K. Peterson-Yantorno, M. Coca-Prados, and M. M. Civan Similarity of A3-adenosine and swelling-activated Cl- channels in nonpigmented ciliary epithelial cells Am J Physiol Cell Physiol, August 1, 2000; 279(2): C440 - C451. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Fischbarg On volume regulation leading to epithelial fluid transport Am J Physiol Cell Physiol, November 1, 1999; 277(5): C1019 - C1019. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |