Ischemic Preconditioning Induces Selective Translocation of Protein Kinase C Isoforms ε and η in the Heart of Conscious Rabbits Without Subcellular Redistribution of Total Protein Kinase C Activity

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Abstract
Considerable controversy surrounds the role of protein kinase C (PKC) in ischemic preconditioning (PC). Previous studies have used pharmacological agents and/or measured total myocardial PKC activity; however, no information is available regarding the effects of PC on individual isoforms in vivo. We performed a comprehensive evaluation (using Western immunoblotting) of the expression and subcellular distribution of all 11 currently known PKC isoforms in the heart of conscious rabbits subjected to four different ischemic PC protocols known to induce early and/or late PC (one, three, or six cycles of 4-minute coronary occlusion [4′O]/4-minute reperfusion [4′R]; four cycles of 5-minute occlusion [5′O]/10-minute reperfusion [10′R]). Ten PKC isoforms (α, β1/β2, γ, δ, ε, ζ, η, ι, λ, and μ) were found to be expressed in the rabbit heart. Quantitative immunoblotting demonstrated that as a subgroup, conventional PKCs (cPKCs) are more abundant than novel PKCs (nPKCs) (1445 versus 313 pg PKC/μg tissue prote...