Slowing aqueous humor secretion is a mainstay of glaucoma therapy. Our goal is to develop a better understanding of cellular mechanisms which regulate secretion. We know secretion is driven by the ion gradients set up by Na,K-ATPase which is most abundant at the basolateral surface of the nonpigmented ciliary epithelium (NPE). Here, we develop and test ideas that function of Na,K-ATPase and other NPE transport proteins can be modulated by changes in cytoplasmic pH (pHi). We have evidence that carbonic anhydrase inhibitors (CAIs) acidify the NPE cell and we hypothesize this could slow aqueous secretion in part because the pH change leads either directly or indirectly to Na,K-ATPase inhibition. In this application, we propose a 5 yr study to examine how ion transport mechanisms in the NPE are set up to respond to pHi changes with the idea in mind that aqueous secretion might be altered in the future by drugs targetted to interfere with cell pHi regulation. The plan comprises three aims.
Aim I is to examine mechanisms by which cytoplasmic acidification could trigger inhibition of Na,K-ATPase in the NPE.
Aim II is to test the hypothesis that mechanisms which control cytoplasmic sodium in the NPE are sensitive to selective carbonic anhydrase IV inhibition.
Aim III is to examine modulation of H+-ATPase function by second messenger pathways. The studies will be conducted with cultured rabbit NPE and freshly isolated rabbit and porcine NPE. Cytoplasmic pH, calcium and sodium concentrations will be determined using fluorescent dyes. Measurements of ouabain-sensitive 86Rb uptake and ATP hydrolysis will be conducted to determine sodium pump (Na,K-ATPase) activity.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY006915-15
Application #
6384554
Study Section
Special Emphasis Panel (ZRG1-MDCN-4 (02))
Program Officer
Liberman, Ellen S
Project Start
1986-07-01
Project End
2002-07-31
Budget Start
2001-08-01
Budget End
2002-07-31
Support Year
15
Fiscal Year
2001
Total Cost
$258,379
Indirect Cost
Name
University of Louisville
Department
Ophthalmology
Type
Schools of Medicine
DUNS #
City
Louisville
State
KY
Country
United States
Zip Code
40292
Mandal, Amritlal; Shahidullah, Mohammad; Delamere, Nicholas A (2018) TRPV1-dependent ERK1/2 activation in porcine lens epithelium. Exp Eye Res 172:128-136
Shahidullah, Mohammad; Mandal, Amritlal; Delamere, Nicholas A (2017) A Role for Calcium-Activated Adenylate Cyclase and Protein Kinase A in the Lens Src Family Kinase and Na,K-ATPase Response to Hyposmotic Stress. Invest Ophthalmol Vis Sci 58:4447-4456
Lee, Jonghwa; Shahidullah, Mohammad; Hotchkiss, Adam et al. (2015) A renal-like organic anion transport system in the ciliary epithelium of the bovine and human eye. Mol Pharmacol 87:697-705
Shahidullah, Mohammad; Mandal, Amritlal; Wei, Guojun et al. (2014) Nitric oxide regulation of Na, K-ATPase activity in ocular ciliary epithelium involves Src family kinase. J Cell Physiol 229:343-52
Shahidullah, Mohammad; Mandal, Amritlal; Wei, Guojun et al. (2014) Nonpigmented ciliary epithelial cells respond to acetazolamide by a soluble adenylyl cyclase mechanism. Invest Ophthalmol Vis Sci 55:187-97
Sanderson, Julie; Dartt, Darlene A; Trinkaus-Randall, Vickery et al. (2014) Purines in the eye: recent evidence for the physiological and pathological role of purines in the RPE, retinal neurons, astrocytes, Müller cells, lens, trabecular meshwork, cornea and lacrimal gland. Exp Eye Res 127:270-9
Shahidullah, Mohammad; Delamere, Nicholas A (2014) Connexins form functional hemichannels in porcine ciliary epithelium. Exp Eye Res 118:20-9
Salyer, Sarah A; Olberding, Jordan R; Distler, Anthony A et al. (2013) Vacuolar ATPase driven potassium transport in highly metastatic breast cancer cells. Biochim Biophys Acta 1832:1734-43
Goldman, Aaron; Chen, HwuDauRw; Khan, Mohammad R et al. (2011) The Na+/H+ exchanger controls deoxycholic acid-induced apoptosis by a H+-activated, Na+-dependent ionic shift in esophageal cells. PLoS One 6:e23835
Goldman, Aaron; Shahidullah, Mohammad; Goldman, David et al. (2010) A novel mechanism of acid and bile acid-induced DNA damage involving Na+/H+ exchanger: implication for Barrett's oesophagus. Gut 59:1606-16

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