Ion pumps and cotransport systems in animal cell membranes maintain cellular ionic composition, transport electrolytes and fluid across epithelia and contribute towards the regulation of cell volume. Thus, it is reasonable to expect that ion pumps in the conjunctival epithelium should play a crucial role in maintaining an optimal tear film, a necessity for a normal functioning ocular surface. However, the transport properties of this epithelium, which interfaces with the tears, are virtually unknown. Therefore, this project will use electrophysiological, radio-labelled tracer and microspectrofluorometric techniques to characterize the transport functions of the rabbit conjunctiva. A thorough understanding of the basic physiology of this cell layer may be relevant to the design of future treatment modalities for dry eye syndrome - a disorder, affecting countless individuals worldwide, that can lead to the loss of vision. The PI will 1) determine the effects of biological activators (i.e., hormones, neurotransmitters, etc.) on macroscopic conductances across the rabbit conjunctival epithelium; 2) determine the nature of the Na+ absorptive process in the apical (tear-facing) surface of the epithelium; 3) complete the characterization of the C1- secreting mechanism; 4) determine the identity of electrically silent transporters that may be present, with emphasis on those usually associated with intracellular pH and cell volume regulation; and 5) determine the diffusional H20 permeability (Pdw) and osmotic permeability (Pf). From these studies the PI expects to be able to construct a model detailing whether this epithelium functions as a fluid secreting or absorbing epithelium. Based on this model, he will devise protocols to modify and possibly reverse the secretory/absorptive properties of the tissue.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY011631-03
Application #
2856953
Study Section
Visual Sciences A Study Section (VISA)
Project Start
1997-01-01
Project End
2001-12-31
Budget Start
1999-01-01
Budget End
1999-12-31
Support Year
3
Fiscal Year
1999
Total Cost
Indirect Cost
Name
Mount Sinai School of Medicine
Department
Ophthalmology
Type
Schools of Medicine
DUNS #
114400633
City
New York
State
NY
Country
United States
Zip Code
10029
Candia, Oscar A (2004) Electrolyte and fluid transport across corneal, conjunctival and lens epithelia. Exp Eye Res 78:527-35
Turner, Helen C; Bernstein, Audrey; Candia, Oscar A (2002) Presence of CFTR in the conjunctival epithelium. Curr Eye Res 24:182-7
Turner, H C; Alvarez, L J; Candia, O A (2001) Identification and localization of acid-base transporters in the conjunctival epithelium. Exp Eye Res 72:519-31
Alvarez, L J; Turner, H C; Zamudio, A C et al. (2001) Serotonin-elicited inhibition of Cl(-) secretion in the rabbit conjunctival epithelium. Am J Physiol Cell Physiol 280:C581-92
To, C H; Do, C W; Zamudio, A C et al. (2001) Model of ionic transport for bovine ciliary epithelium: effects of acetazolamide and HCO. Am J Physiol Cell Physiol 280:C1521-30
Turner, H C; Alvarez, L J; Bildin, V N et al. (2000) Immunolocalization of Na-K-ATPase, Na-K-Cl and Na-glucose cotransporters in the conjunctival epithelium. Curr Eye Res 21:843-50
Turner, H C; Alvarez, L J; Candia, O A (2000) Cyclic AMP-dependent stimulation of basolateral K(+)conductance in the rabbit conjunctival epithelium. Exp Eye Res 70:295-305
Alvarez, L J; Candia, O A; Turner, H C et al. (1999) Phorbol ester modulation of active ion transport across the rabbit conjunctival epithelium. Exp Eye Res 69:33-44
Candia, O A; Shi, X P; Alvarez, L J (1998) Reduction in water permeability of the rabbit conjunctival epithelium by hypotonicity. Exp Eye Res 66:615-24