Propofol-induced activation of protein kinase C isoforms in adult rat ventricular myocytes

Abstract

Background: Myocardial protection by anesthetics is known to involve activation of protein kinase C (PKC). The authors' objective was to identify the PKC isoforms activated by propofol in rat ventricular myocytes. They also assessed the intracellular location of individual PKC isoforms before and after treatment with propofol. Methods: Freshly isolated ventricular myocytes were obtained from adult rat hearts. Immunoblot analysis of cardiomyocyte subcellular fractions was used to assess translocation of individual PKC isoforms before and after exposure to propofol. An enzyme-linked immunosorbent assay kit was used for measuring PKC activity. Immunocytochemistry and confocal microscopy were used to visualize the intracellular location of the individual PKC isoforms. Results: Under baseline conditions, PKC-α, PKC-δ, and PKC-ζ were associated with both the cytosolic and membrane fractions, whereas PKC-ε was exclusively located in the cytosolic fraction. Propofol (10 μM) caused translocation of PKC-α, PKC-δ, PKC-ε, and PKC-ζ from cytosolic to membrane fraction and increased total PKC activity (211 ± 17% of baseline; P = 0.003) in a dose-dependent manner. Immunocytochemical localization of the individual PKC isoforms demonstrated that propofol caused translocation of PKC-α to the intercalated discs and z-lines; PKC-δ to the perinuclear region; PKC-ε to sites associated with the z-lines, intercalated discs, and the sarcolemma; and PKC-ζ to the nucleus. Conclusions: These results demonstrate that propofol causes an increase in PKC activity in rat ventricular myocytes. Propofol stimulates translocation of PKC-α, PKC-δ, PKC-ε, and PKC-ζ to distinct intracellular sites in cardiomyocytes. This may be a fundamentally important cellular mechanism of anesthesia-induced myocardial protection in the setting of ischemia-reperfusion injury. © 2006 American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc.