The primary goal of the proposed research plan is to provide Tracy T. Nguyen, OD with the comprehensive didactic, laboratory and clinical training necessary to develop into an independent researcher in the area of corneal physiology. The multidisciplinary training plan will be under the guidance of mentor Joseph Bonanno, PhD and co-mentor Clark Springs, MD. The training plan will span 3 years of a Ph.D. program followed by a 2 year post-doctoral training. The proposed research program will focus on the mechanism for efficient removal of lactic acidic from the cornea. The cornea is a very glycolytic tissue and therefore produces large amounts of lactic acid. This proposal will investigate the general hypothesjs that bicarbonate transporters of the corneal endothelial pump mechanism, in conjunction with carbonic anhydrase (CA) activity act to facilitate lactic acid efflux from the stroma into the anterior chamber. Failure to remove lactic acid will result in corneal edema and a lower stromal pH. The hypotheses are: 1) Transport of lactic acid across the corneal endothelium is via monocarboxylate transports (MCTs) 2) MCTs play a role in lactate:H+ transport in vivo. 3) HCO3- together with CA II &CA XII buffers the basolateral lactate:H+ influx and HCO3- together with CA IV buffers apical lactate:H+ efflux thereby facilitating the net flux of lactate from stroma to anterior chamber. 4) Corneas with diminishing endothelial function (i.e. reduced endothelial cell density, endothelial guttata) have reduced capacity to remove lactic acid and should show a greater corneal thickness change and greater stromal Ph drop following instillation a carbonic anhydrase inhibitor. The first part of the research project will use molecular and cell biology approaches to identify and locate lactate:H+ cotransporters, measure cellular and transcellular lactate fluxes, use siRNA approaches to knockdown transporter expression and examine the effects of bicarbonate and carbonic anhydrase inhibitors on lactate fluxes and corneal thickness both in vitro and in vivo. The later part of the project will examine the relationship between corneal thickness with a carbonic anhydrase inhibitor and stromal pH in both normal subjects and subjects with early Fuch's dystrophy.
|Nguyen, Tracy T; Bonanno, Joseph A (2012) Lactate-HÃ½Ã½Ã½ transport is a significant component of the in vivo corneal endothelial pump. Invest Ophthalmol Vis Sci 53:2020-9|
|Nguyen, Tracy T; Bonanno, Joseph A (2011) Bicarbonate, NBCe1, NHE, and carbonic anhydrase activity enhance lactate-H+ transport in bovine corneal endothelium. Invest Ophthalmol Vis Sci 52:8086-93|