Fig. 6. Elevation of cytoplasmic CaTs is not sufficient to enhance nuclear CaTs. (A) Original recordings of cytoplasmic (black) and nuclear CaTs (red) of two atrial myocytes before and during exposure to 10 nM ET (left) or 10 nM ISO (right). (B) Average values of peak systolic [Ca²⁺] in the cytoplasm (black) and in the nucleus (red) following application of ET (n=24), ISO (n=10) or 4 mM extracellular Ca²⁺ (`4Ca'; n=6). (C) Normalised ratio of nuclear to cytoplasmic [Ca²⁺] following application of ET (n=24), ISO (n=10) or 4 mM extracellular Ca²⁺ (n=6). In B and C, values were normalised to the initial control (=100%). **, P<0.01 versus initial control.