Inhibition of protein kinase C ¦ÂII isoform rescues glucose toxicity-induced cardiomyocyte contractile dysfunction: Role of mitochondria

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• 作者：Zikuan Wang ; Yanchun Zhang ; Jingjing Guo ; Kuihua Jin ; Jun Li ; Xiaolan Guo ; Glenda I. Scott ; Qiangsun Zheng ; Jun Ren
• 关键词：Glucose toxicity ; Contractile function ; Cardiomyocytes ; Protein kinase C isoform
• 刊名：Life Sciences
• 出版年：2013
• 出版时间：30 July, 2013
• 年：2013
• 卷：93
• 期：2-3
• 页码：116-124
• 全文大小：1664 K

文摘

Aims

Hyperglycemia leads to cytotoxicity in the heart. Although theories were postulated for glucose toxicity-induced cardiomyocyte dysfunction including oxidative stress, the mechanism involved still remains unclear. Recent evidence has depicted a role of protein kinase C (PKC) in diabetic complications while high concentrations of glucose stimulate PKC. This study examined the role of PKC¦ÂII in glucose toxicity-induced cardiomyocyte contractile and intracellular Ca^2 + aberrations.

Main methods

Adult rat cardiomyocytes were maintained in normal (NG, 5.5 mM) or high glucose (HG, 25.5 mM) medium for 12 h. Contractile and intracellular Ca^2 + properties were measured using a video edge-detection system including peak shortening (PS), maximal velocity of shortening/relengthening (¡À dL/dt), time-to-PS (TPS), time-to-90 % relengthening (TR₉₀), rise in intracellular Ca^2 + Fura-2 fluorescence intensity and intracellular Ca^2 + decay. Production of ROS/O₂^? and mitochondrial integrity were examined using fluorescence imaging, aconitase activity and Western blotting.

Key findings

High glucose triggered abnormal contractile and intracellular Ca^2 + properties including reduced PS, ¡À dL/dt, prolonged TR₉₀, decreased electrically-stimulated rise in intracellular Ca^2 + and delayed intracellular Ca^2 + clearance, the effects of which were ablated by the PKC¦ÂII inhibitor LY333531. Inhibition of PKC¦ÂII rescued glucose toxicity-induced generation of ROS and O₂^?, apoptosis, cell death and mitochondrial injury (reduced aconitase activity, UCP-2 and PGC-1¦Á). In vitro studies revealed that PKC¦ÂII inhibition-induced beneficial effects were mimicked by the NADPH oxidase inhibitor apocynin and were canceled off by mitochondrial uncoupling using FCCP.

Significance

These findings suggest the therapeutic potential of specific inhibition of PKC¦ÂII isoform in the management of hyperglycemia-induced cardiac complications.