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Qian Garrett, Neeta Khandekar, Peter A. Simmons, Joseph G. Vehige, Jr., Mark D. Willcox; Changes In Corneal Epithelial Cell Volume In Response To Hyperosmotic Stress In The Absence Or Presence Of Carnitine. Invest. Ophthalmol. Vis. Sci. 2012;53(14):565.
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The compatible solute, carnitine, has been reported to help stabilize human corneal epithelial cells under hyperosmotic conditions, leading to rapid and consistent improvements in the signs and symptoms of dry eye patients. Additionally, we have identified the transporters for carnitine on human corneal limbal epithelial (HCLE) cells and the sodium-dependent mechanism by which carnitine is transported in HCLE cells. The present study tested the hypothesis that carnitine assists cells to compensate for hypertonic stress through stabilizing cell volume and preventing hyperosmotic-stress induced shrinkage.
Cultured HCLE cells were exposed to culture medium with or without carnitine (10 mM) at 300 mOsm (isotonic) and 500 mOsm (hyperosmotic) for 16 h. Flow cytometry was performed to determine the cell volume changes based on the forward and side scatter values detected.
The percentage of shrunken cells significantly increased when the cells were subjected to 500 mOsm hyperosmotic conditions (~27%) compared with populations subjected to the isotonic 300 mOsm environment (~5%). However, the percentage of these shrunken cells markedly reduced when the cells were treated with 10 mM carnitine in 500 mOsm hyperosmlar media (~15%).
Carnitine is able to regulate cell volume under hyperosmolar stress preventing subsequent apoptosis.
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