Fig. 5.

Effect of the protein kinase A inhibitor, H-89. A, i: representative Ca²⁺ current traces at +10 mV in an atrial myocyte from a Sham-operated rat in control Tyrode’s, in the presence of 10 μmol/l H-89, and in the presence of 10 μmol/l H-89 and 1 μmol/l norepinephrine (NE). A, ii: mean I_CaL density-voltage relations from Sham myocytes (n/N = 8/4) in control (black-filled circles), in the presence of 10 μmol/l H-89 (gray-filled circles) and in the presence of 10 μmol/l H-89 and 1 μmol/l NE (open circles). B, i: representative Ca²⁺ current traces in an atrial myocyte from a CAL rat in control Tyrode’s, in the presence of 10 μmol/l H-89, and in the presence of 10 μmol/l H-89 and 1 μmol/l NE. Right-pointing arrows indicate zero current level. B, ii: mean I_CaL density-voltage relations from CAL myocytes (n/N = 13/4) in control (black filled squares), in the presence of 10 μmol/l H-89 (gray-filled squares) and in the presence of 10 μmol/l H-89 and 1 μmol/l NE (open squares).