Key result
Perfusion of guinea pig hearts with protein kinase C activators PMA or D8G did not increase phosphorylation of phospholamban or troponin I and C in intact beating hearts.
Population
Langendorff-perfused guinea pig hearts
Comparison
Phorbol 12-myristate 13-acetate or… vs Inactive phorbol ester in the presence of…
Design
Preclinical
Authors
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PKC activators fail to phosphorylate phospholamban or troponin I/C in intact hearts; challenges in vitro assumptions and leaves open in vivo cardiac regulation.
Cardiac regulatory phosphoproteins like phospholamban and troponin I are not substrates for protein kinase C in intact beating hearts, despite being substrates in vitro.
Édes et al. (1990) studied this question. Phorbol 12-myristate 13-acetate (PMA) or 1,2-dioctanoylglycerol (D8G) vs. Inactive phorbol ester (4 alpha-phorbol 12,13-didecanoate) was evaluated on Phosphorylation of phospholamban and troponin I and C (32P incorporation). Perfusion of guinea pig hearts with protein kinase C activators PMA or D8G did not increase phosphorylation of phospholamban or troponin I and C in intact beating hearts.
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