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J. Makita, J. Randazzo, K. Blessing, K. Yu, K.–I. Hosoya, T. Terasaki, P.F. Kador; Polyol Formation in Rat Retinal Capillary Pericyte and Endothelial Cells . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4240.
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© ARVO (1962-2015); The Authors (2016-present)
The selective destruction of retinal capillary pericytes is reported to be the hallmark of diabetic retinopathy. In the dog, pericyte destruction rapidly occurs and in vitro and in vivo studies indicate that only the retinal pericytes and not endothelial cells contain aldose reductase (AR) and accumulate polyols and that this accumulation initiates apoptosis. In the rat, several reports suggest that both pericytes and endothelial cells contain AR. To establish whether species differences in retinal capillaries cells exist, we have investigated Polyol Pathway activity in rat retinal capillary pericyte (TR–rPCT) and endothelial (TR–iBRB) cell lines.
The TR–rPCT and TR–iBRB cell lines were obtained from transgenic rat harboring the temperature–sensitive simian virus 40 (SV 40) large T–antigen gene. After re–cloning these cells, each cell line was grown at 33oC on rat tail type I collagen coated plates with DMEM medium containing 10% FBS. The cells examined for their ability to take up acetylated low density lipoprotein (Ac–LDL) and probed with antibodies against rat smooth muscle actin, rat lens AR and rat kidney aldehyde reductase (ALR). The cells were cultured for up to 72 hours in media containing 50 mM glucose or galactose with/without 10µM of the AR inhibitor AL–1576. Polyol levels were determined by HPLC.
Characteristically, only pericytes contained smooth muscle actin while only the endothelial cells accumulated acetylated low density lipoprotein (Ac–LDL). Antibody studies indicated that AR is present in both cells; however, AR staining in endothelial cells was much less than in pericytes. Weak staining for ALR was also observed in both cells. Culture of both cells in 50 mM glucose or galactose resulted in significant accumulation of polyols in the pericytes but little accumulation of galactitol and no accumulation of sorbitol in the endothelial cells. Polyol accumulation in the pericytes resulted in increased cellular permeability with increased levels of polyols into the media. In contrast, no permeability changes were observed in the endothelial cells.
The differences between AR levels in the dog and rat retinal capillary cells and their accumulation of polyols may explain the differences observed in the development of retinal lesions between the two species.
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