Protein kinase C and preconditioning: Role of the sarcoplasmic reticulum

Ken Yamamura, Charles Steenbergen, Elizabeth Murphy

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


Activation of protein kinase C (PKC) is cardioprotective, but the mechanism(s) by which PKC mediates protection is not fully understood. Inasmuch as PKC has been well documented to modulate sarcoplasmic reticulum (SR) Ca 2+ and because altered SR Ca2+ handling during ischemia is involved in cardioprotection, we examined the role of PKC-mediated alterations of SR Ca2+ in cardioprotection. Using isolated adult rat ventricular myocytes, we found that addition of 1,2-dioctanoyl-sn-glycerol (DOG), to activate PKC under conditions that reduced myocyte death associated with simulated ischemia and reperfusion, also reduced SR Ca2+. Cell death was 57.9 ± 2.9% and 47.3 ± 1.8% in untreated and DOG-treated myocytes, respectively (P < 0.05). Using fura 2 fluorescence to monitor Ca2+ transients and caffeine-releasable SR Ca2+. we examined the effect of DOG on SR Ca2+. Caffeine-releasable SR Ca 2+ was significantly reduced (by ∼65%) after 10 min of DOG treatment compared with untreated myocytes (P < 0.05). From our examination of the mechanism by which PKC alters SR Ca2+, we present the novel finding that DOG treatment reduced the phosphorylation of phospholamban (PLB) at Ser16. This effect is mediated by PKC-ε, because a PKC-ε-selective inhibitory peptide blocked the DOG-mediated decrease in phosphorylation of PLB and abolished the DOG-induced reduction in caffeine-releasable SR Ca2+. Using immunoprecipitation, we further demonstrated that DOG increased the association between protein phosphatase 1 and PLB. These data suggest that activated PKC-ε reduces SR Ca2+ content through PLB dephosphorylation and that reduced SR Ca2+ may be important in cardioprotection.

Original languageEnglish (US)
Pages (from-to)H2484-H2490
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number6 58-6
StatePublished - Dec 2005
Externally publishedYes


  • 1,2-dioctanoyl-sn-glycerol
  • Calcium
  • Protein kinase C-ε
  • Protein phosphatase 1

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)


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