Gö 6983: A Fast Acting Protein Kinase C Inhibitor that Attenuates Myocardial Ischemia/Reperfusion Injury

Abstract

Reperfusion injury is characterized by a decrease in endothelial release of nitric oxide within 5 min after reperfusion, increased leukocyte-endothelium interaction, and transmigration of leukocytes into the myocardium, producing cardiac contractile dysfunction. Gö 6983 is a fast acting, lipid soluble, broad spectrum protein kinase C inhibitor. When administered at the beginning of reperfusion, it can restore cardiac function within 5 min and attenuate the deleterious effects associated with acute ischemia/reperfusion. Gö 6983 may offer greater cardioprotection than other broad-spectrum PKC inhibitors in postischemic reperfusion injury because it inhibits PKC(zeta) as well as four other isoforms. The cardioprotection is associated with decreased leukocyte superoxide release and increased endothelial derived nitric oxide from vascular tissue. In vitro studies of human tissue showed that Gö 6983 significantly inhibited antigen-induced superoxide release from leukocytes of patients previously sensitized to tree pollen. In human vascular tissue, Gö 6983 inhibited intracellular Ca(2+) accumulation, suggesting a mechanism for its vasodilator properties. These studies suggest that Gö 6983 would be an effective compound to use in a clinical ischemia/reperfusion setting of organ transplantation and/or cerebral ischemia where inhibiting superoxide release and vasoconstriction in postischemic tissues would allow for better restoration of organ function during reperfusion. However, given the broad-spectrum action of Gö 6983, careful titration of the dose regimen would be recommended to ensure a successful outcome in the setting of organ transplantation and/or cerebral ischemia.

Protein Kinase C Beta II (PKCβII) Peptide Inhibitor Exerts Cardioprotective Effects in Myocardial Ischemia/Reperfusion Injury

“…Hearts were rapidly excised and perfused at a constant pressure of 80 mm Hg with a modified physiological Krebs' buffer aerated with 95% O2-5% CO2 maintained at 37 o C and pH 7.3-7.4 by Langendorff preparation. Hearts were subjected to 15 min of baseline perfusion, 30 min of ischemia, and a 90 min reperfusion period [8]. Five ml of plasma (control MI/R hearts), or plasma containing cell-permeable PKC II peptide inhibitor (N-Myr-SLNPEWNET, MW=1300 g/mol, 10-20μM Genemed Synthesis Inc., San Antonio, TX) ( Figure 2) were infused during the first 5min of reperfusion by a side arm line proximal to the heart inflow at a rate of 1ml/min.…”

“…PKC II activity is increased in animal models of MI/R and known to exacerbate tissue injury [4,5]. PKC II is known to increase NADPH oxidase activity in leukocytes, endothelial cells and cardiac myocytes via phox47 phosphorylation, and decrease endothelial NO synthase (eNOS) activity via phosphorylation of Thr 495 [6][7][8]. NADPH oxidase produces superoxide (SO) and quenches endothelial derived NO in cardiac endothelial cells.…”

“…PKC II peptide inhibitor mechanism of action ( Figure 1 right) is to inhibit PKC II translocation to cellular substrates such as eNOS, NADPH oxidase, and mitochondrial p66Shc protein that increase ROS leading to opening of the MPTP which in turn leads to consequent release of proapoptotic factors into the cytosol [9,10]. We've previously shown that PKC II peptide inhibitor restored post-reperfused cardiac function and reduced polymorphornuclear leukocyte (PMN) infiltration in isolated rat hearts subjected to MI(20min)/R(45min) reperfused with PMNs [8]. In addition, the use of PKC II peptide inhibitor (10-20 μM) correlated with the inhibition of SO release from isolated leukocytes suggesting that this dose range maybe effective in attenuating ROS production [11].…”

Comparing the Effectiveness of TAT and Myristoylation of gp91ds on Leukocyte Superoxide (SO) Release

“…Activation of NOX2 requires the assembly of cytosolic subunits (p47 phox , p40 phox , p67 phox , Rac) to plasma membrane subunits (gp91 phox and p22 phox ) [1]. NADPH oxidase is activated during I/R injury via cytokine receptor stimulation or chemotactic factor (N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP, MW= 438 g/mol) and utilizes molecular oxygen to produce SO [2] (Figure 1). [2].…”

“…NADPH oxidase is activated during I/R injury via cytokine receptor stimulation or chemotactic factor (N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP, MW= 438 g/mol) and utilizes molecular oxygen to produce SO [2] (Figure 1). [2].…”