We propose to examine mechanisms whereby the hyperglycemia of diabetes mellitus and its resulting two metabolic perturbations, increased polyol pathway activity and decreased myo-inositor content in retinal capillary pericytes (mural cells) may result in retinal capillary pericyte loss. Loss of pericyte may impair the integrity of the retinal microvascularture, leading to the breakdown of blood-ocular-barrier. The biochemical mechanisms by which high glucose causes reduction of pericyte viability in vitro and in vivo and the role of these two metabolic perturbations are the principal objectives in the present application. Since the decreased cellular myo-inositol may cause a reduction of phosphoinositides, including phosphatidylinositol 4,5 bisphosphate (PIP2); and hydrolysis of PIP2 produces novel second messengers (inositol trisphosphate (IP3) and diacylglycerol (DG)) which are implicated in cell proliferation, it is likely that alterations in myo-inositol metabolism induced by high glucose may contribute to a decrease in the rate of retinal capillary pericyte proliferation. In the proposed investigation we will study the effect of high glucose on the inositol metabolism. The production of phosphoinositides and second messengers (IP3 and DG) will be quantitatively determined. Myo-inositol synthase or PIP2 phosphodiesterase activity which may be important for maintaining myo-inositol or PIP2 levels respectively, will be assayed. Under """"""""normal"""""""" and high glucose conditions the incorporation of tritium-labelled thymidine, an index of cell proliferation, and cellular sorbitol and myo-inositol levels will be simultaneously determined. In the proposed studies, the normalization of high glucose or decreased myo-inositol by insulin or myo-inositol supplementation in culture medium, respectively, and reversal of elevated polyol pathway activity by aldose reductase inhibitors may be employed as in vitro """"""""therapy"""""""" to correct the decreased rate of retinal capillary pericyte proliferation.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
1R01EY006563-01
Application #
3262868
Study Section
Visual Sciences A Study Section (VISA)
Project Start
1986-08-01
Project End
1989-07-31
Budget Start
1986-08-01
Budget End
1987-07-31
Support Year
1
Fiscal Year
1986
Total Cost
Indirect Cost
Name
Peking Union Medical College Hospital
Department
Type
DUNS #
City
Beijing
State
Country
China
Zip Code
Li, W; Liu, X (1994) Interaction between phosphoinositide-phospholipase C and phosphatidylcholine-phospholipase D in plasma membranes of retinal capillary pericytes. Ophthalmic Res 26:189-95
Li, W; Wang, W; Liu, X (1994) Comparative study of high-glucose effect on phosphatidylcholine hydrolysis of cultured retinal capillary pericytes and endothelial cells. Biochim Biophys Acta 1222:339-47
Li, W; Liu, X; Yanoff, M (1994) Different responses of choriocapillary endothelial cells and retinal capillary endothelial cells to mitogenic and vasoactive factors. Chin Med Sci J 9:96-9
Li, W; Tao, L; Yanoff, M (1994) Agonist-induced phosphatidylinositide breakdown and mitogenesis in retinal capillary pericytes. Ophthalmic Res 26:36-40
Liu, X; Li, W (1993) Isolation, culture and characterization of bovine choriocapillary endothelial cells. Exp Eye Res 57:37-44
Tao, L; Li, W (1992) Rapid and sensitive anion-exchange high-performance liquid chromatographic determination of radiolabeled inositol phosphates and inositol trisphosphate isomers in cellular systems. J Chromatogr 607:19-24
Li, W; Ye, X; Tao, L et al. (1992) Comparison and characterization of retinal pericytes and retinal pigment epithelial cells on subcellular IP3-sensitive Ca2+ pools. Cell Prolif 25:651-62
Li, W Y; Zhou, Q; Qin, M et al. (1991) Reduced absolute rate of myo-inositol biosynthesis of cultured bovine retinal capillary pericytes in high glucose. Exp Eye Res 52:569-73
Li, W Y; Zhou, Q; Tang, L et al. (1990) Intramural pericyte degeneration in early diabetic retinopathy study in vitro. Chin Med J (Engl) 103:7-13
Li, W Y; Tang, L; Zhou, Q et al. (1989) DNA-synthesis regulation and correlation with inositol trisphosphate levels in cultured bovine retinal capillary pericytes. Exp Eye Res 49:677-83

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