Correlation of diacylglycerol level and protein kinase C activity in rat retina to retinal circulation

T. Shiba, T. Inoguchi, J. R. Sportsman, W. F. Heath, S. Bursell, G. L. King

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    304 Citations (Scopus)

    Abstract

    The increases in diacylglycerol (DAG) level and protein kinase C (PKC) activity have been characterized biochemically and functionally in the retina and the brain of diabetic rats as well as in cultured vascular cells. PKC specific activities were increased in the membraneous fraction of retina from streptozotocin (STZ)-induced diabetic rats and the genetically determined diabetic BB rats, respectively, after 1 or 2 wk of diabetes, compared with control. The ratio of total PKC activities from membraneous and cytosol fractions was also increased in the retina of diabetic rats. With diabetes, all the isoenzymes and the total DAG level were increased in the rat retina, whereas no changes were found in the rat brain. Insulin treatment normalized plasma glucose levels and partially prevented the increases in the membraneous PKC activity and all the isoenzymes in the retina. In the retinal endothelial cells, the total DAG level and PKC specific activities are increased by 36 and 22%, respectively, in the membraneous pool when the glucose levels are changed from 5.5 to 22 mM. Activation of PKC activity and isoform βII by the vitreal injection of phorbol dibutyrate mimicked the abnormal retinal blood circulation observed in diabetic rats (2.22 ± 0.24 vs. 1.83 ± 0.40 s). Thus diabetes and elevated glucose levels will increase DAG level and PKC activities and its isoenzyme specifically in vascular cells and may affect retinal hemodynamics.

    Original languageEnglish
    Pages (from-to)E783-E793
    JournalAmerican Journal of Physiology - Endocrinology and Metabolism
    Volume265
    Issue number5 28-5
    DOIs
    Publication statusPublished - 1993

    All Science Journal Classification (ASJC) codes

    • Endocrinology, Diabetes and Metabolism
    • Physiology
    • Physiology (medical)

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