Fig. 2From: The mechanism of increased postnatal heart rate and sinoatrial node pacemaker activity in miceDevelopmental changes in SAN pacemaking activity. a Time course of changes in in vivo HR with (filled triangles) or without pharmacological blockade of autonomic nervous systems (filled squares) and spontaneous beating rate of SAN preparations (open circles) during postnatal development. Body weight is also shown in the lower graph. Number of experiments is indicated near each data. b Representative sweeps of spontaneous action potentials recorded in SAN cells of neonatal (left) and adult (right) mice. Data are mean ± SEMBack to article page