Protein kinase C-mediated calcium signaling as the basis for cardiomyocyte plasticity.

Protein kinase C is the superfamily of intracellular effector molecules which control crucial cellular functions. Here, we for the first time did the percentage estimation of all known PKC and PKC-related isozymes at the individual cadiomyocyte level. Broad spectrum of PKC transcripts is expressed in the left ventricular myocytes. In addition to the well-known 'heart-specific' PKCα, cardiomyocytes have the high expression levels of PKCN1, PKCδ, PKCD2, PKCε. In general, we detected all PKC isoforms excluding PKCη. In cardiomyocytes PKC activity tonically regulates voltage-gated Ca-currents, intracellular Ca level and nitric oxide (NO) production. Imidazoline receptor of the first type (IR)-mediated induction of the PKC activity positively modulates Ca release through ryanodine receptor (RyR), increasing the Ca leakage in the cytosol. In cardiomyocytes with the Ca-overloaded regions of > 9-10 μm size, the local PKC-induced Ca signaling is transformed to global accompanied by spontaneous Ca waves propagation across the entire cell perimeter. Such switching of Ca signaling in cardiac cells can be important for the development of several cardiovascular pathologies and/or myocardial plasticity at the cardiomyocyte level.