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Jia Wang, Laura D. Carbone, Mitchell A. Watsky; Receptor-Mediated Activation of a Cl− Current by LPA and S1P in Cultured Corneal Keratocytes. Invest. Ophthalmol. Vis. Sci. 2002;43(10):3202-3208.
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purpose. This study was designed to examine the effects of lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) on Cl− currents (IClLPA) in cultured corneal keratocytes isolated from the corneas of New Zealand White rabbits.
methods. IClLPA and resting voltages were recorded with the amphotericin perforated-patch technique. Phenotype was determined with antibodies to α-smooth muscle actin.
results. Keratocytes cultured in serum have a phenotype (myofibroblast) and ionic currents similar to those of keratocytes isolated directly from corneas during wound healing. LPA and S1P both activated IClLPA in a dose-dependent manner, and the LPA receptor–specific antagonist dioctyl-glycerol pyrophosphate (DGPP) blocked the LPA response, but not the S1P response. In addition, a relatively inactive form of LPA (LPA 8:0) was relatively ineffective in activating IClLPA. Activation of IClLPA significantly depolarized the cells, and this depolarization was reversed by blocking IClLPA with 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid (DIDS) or 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB).
conclusions. These results demonstrate that activation of IClLPA by LPA in cultured corneal keratocytes is receptor mediated and that IClLPA can also be activated by S1P. From a functional standpoint, this work confirms that the current, which is typically thought of as purely volume-activated, can be activated through a receptor. In addition, activation of IClLPA results in depolarization of the keratocyte. Finally, this work demonstrates that cultured corneal keratocytes can act as a model for the study of ion channel function in keratocytes during corneal wound healing.
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