title: Correlation of diacylglycerol level and protein kinase C activity in rat retina to retinal circulation.
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 beta II 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.
authors.affiliation: Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02215.
authors.forename: T
authors.initials: T
authors.lastname: Shiba
authors.forename: T
authors.initials: T
authors.lastname: Inoguchi
authors.forename: J R
authors.initials: JR
authors.lastname: Sportsman
authors.forename: W F
authors.initials: WF
authors.lastname: Heath
authors.forename: S
authors.initials: S
authors.lastname: Bursell
authors.forename: G L
authors.initials: GL
authors.lastname: King
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D001921:Brain / Q000201:enzymology / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology; D003600:Cytosol / Q000201:enzymology; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism / Q000503:physiopathology*; D003922:Diabetes Mellitus, Type 1 / Q000378:metabolism / Q000503:physiopathology*; D004075:Diglycerides / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004730:Endothelium, Vascular / Q000201:enzymology / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011493:Protein Kinase C / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D011913:Rats, Inbred BB; D017207:Rats, Sprague-Dawley; D012160:Retina / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D012171:Retinal Vessels / Q000187:drug effects / Q000502:physiology* / Q000503:physiopathology
chemical_list: D001786:Blood Glucose; D004075:Diglycerides; D007328:Insulin; D007527:Isoenzymes; D010446:Peptide Fragments; D015240:Phorbol 12,13-Dibutyrate; D011493:Protein Kinase C