Nuclear Ca2+ regulates cardiomyocyte function

In the heart, cytosolic Ca 2+ signals are well-characterized events that participate in the activation of cell contraction. In contrast, nuclear Ca 2+ contribution to cardiomyocyte function remains elusive. Here, we examined functional consequences of buffering nuclear Ca 2+ in neonatal cardiomyocytes. We report that cardiomyocytes contain a nucleoplasmic reticu- lum, which expresses both ryanodine receptor (RyR) and inositol 1,4,5-trisphosphate receptor