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B. Gesslein, L. Gustafsson, A. Wackenfors, F. Ghosh, M. Malmsjo; Retinal Ischemia Reperfusion Decreases Protein Kinase C Levels in the Porcine Neuroretina and Retinal Arteries. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3435.
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Identification of intracellular transduction pathways that are activated in ischemia related conditions of the eye may be important in order to find pharmacological targets to prevent retinal injury. The regulation of protein kinase C (PKC) has been implicated in cerebral and cardiac ischemia and studies on PKC and retinal ischemia have started to emerge. Nevertheless, knowledge about the role for PKC in retinal ischemia is still fairly limited. Alterations in the levels of PKC subtypes have been studied in the neuroretina, while little is known about the effects in the retinal vasculature. Our aim was to examine protein kinase C (PKC) in a novel porcine model of pressure induced ischemia reperfusion were the retinal vasculature was isolated.
Retinal ischemia, followed by 5, 12 or 20 hours of reperfusion, was induced by elevating IOP in porcine eyes. mRNA expression and protein levels were quantified using real-time PCR and Western blot, respectively. The neuroretina and retinal arteries were studied separately.
The PKCα, ß1 and ß2 mRNA levels were decreased after ischemia reperfusion both in the neuroretina and in the retinal arteries (Figure 1). Likewise the protein levels of both non-phosphorylated and phosphorylated (activated) PKCα, ß1 and ß2 were decreased following ischemia reperfusion.
Taken together these results demonstrate that PKC levels are decreased, both in the neuroretina and in the retinal arteries, following pressure-induced retinal ischemia. The mechanism underlying this decrease in PKC mRNA and protein levels is not known, but may depend on a decreased transcription and translation of PKC, triggered by humoral factors that are altered during ischemia.Figure 1: PKCα, PKCß1, PKCß2 mRNA expression levels in (A, C and E) the neuroretina and in (B, D and F) the retinal arteries after ischemia and reperfusion (5, 12 or 20 hours). The PKC mRNA levels were calculated relative to the housekeeping gene ß-actin and the change after ischemia reperfusion versus sham are presented as mean values ± S.E.M.
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