This research is aimed at understanding the basis for the conductance of the crystalline lens, how this conductance is controlled, and how it is altered by the process of cataractogenesis. The long-term aim is to develop ways to therapeutically control conductance so as to slow the progress of cataract formation. In this proposal, the distribution of lens gap junctions will be mapped by intracellular dye injections through microelectrodes followed by an image analyzer based quantitation of the dye spread at many lens locations. Direct measurements of the conductance, voltage dependence, Ca dependence, pH dependence, and the calmodulin dependence of the gap junctions connecting the two cells are planned using a 2-cell voltage clamp technique. Epithelial- epithelial, epithelial-fiber, and fiber-fiber junctions will be characterized. These results will be verified with measurements of the diffusion of fluorescent substances between the cells. The electrical and dye coupling as well as transepithelial cleft resistance from capsule-epithelium monolayers will be measured. Spatial differences in the diffusion in the extracellular space near the lens surface will be determined. The properties and distribution of ionic channels in lens membranes will be characterized using patch clamp techniques and noise analysis. Blockers for the channels will be found. All of these methodologies will be applied to normal rat lenses and to rat lenses early in formation of galactose cataracts to identify conductance mechanisms involved in the cataractogenesis. We will attempt to alter the cataract process through the use of channel blocking drugs.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
4R37EY003282-15
Application #
3483978
Study Section
Special Emphasis Panel (NSS)
Project Start
1987-06-01
Project End
1998-05-31
Budget Start
1993-06-01
Budget End
1994-05-31
Support Year
15
Fiscal Year
1993
Total Cost
Indirect Cost
Name
Mayo Clinic, Rochester
Department
Type
DUNS #
City
Rochester
State
MN
Country
United States
Zip Code
55905
Rae, J L; Levis, R A (2004) Fabrication of patch pipets. Curr Protoc Neurosci Chapter 6:Unit 6.3
Mathias, Richard T; Rae, James L (2004) The lens: local transport and global transparency. Exp Eye Res 78:689-98
Ou, Yijun; Strege, Peter; Miller, Steven M et al. (2003) Syntrophin gamma 2 regulates SCN5A gating by a PDZ domain-mediated interaction. J Biol Chem 278:1915-23
Rae, James L; Levis, Richard A (2002) Single-cell electroporation. Pflugers Arch 443:664-70
Rae, J L; Shepard, A R (2000) Kir2.1 Potassium channels and corneal epithelia. Curr Eye Res 20:144-52
Rae, J L; Shepard, A R (2000) Kv3.3 potassium channels in lens epithelium and corneal endothelium. Exp Eye Res 70:339-48
Rich, A; Farrugia, G; Rae, J L (1999) Effects of melatonin on ionic currents in cultured ocular tissues. Am J Physiol 276:C923-9
Shepard, A R; Rae, J L (1999) Electrically silent potassium channel subunits from human lens epithelium. Am J Physiol 277:C412-24
Shepard, A R; Rae, J L (1999) ""Microprep"" method for rapidly isolating plasmid DNAs for restriction enzyme analysis. Biotechniques 26:868-70
Rae, J L; Shepard, A R (1998) Molecular biology and electrophysiology of calcium-activated potassium channels from lens epithelium. Curr Eye Res 17:264-75

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