Fig. 7
From: The mechanism of increased postnatal heart rate and sinoatrial node pacemaker activity in mice
I CaT in isolated SAN cells from neonatal and adult mice. a Representative traces showing the isolation of I CaT. Superimposed current traces recorded by 300-ms depolarizing pulses from a holding potential of −100 and −60 mV in adult SAN cells. The difference current is shown in the right panel. b Superimposed current traces were difference currents at various test potentials obtained from neonatal (upper traces) and adult (lower traces) by the pulse protocols shown in (a). Dotted lines indicate the zero current level. c Averaged current–voltage relationships of I CaT in pacemaker cells for the initial current (circles) and the current at the end of the 500-ms pulses (squares). Open and filled symbols indicate neonatal and adult mice, respectively. d Steady-state inactivation curves for I CaT in SAN cells from neonatal (open circles) and adult (filled circles) mice. The smooth curves were drawn by the least squares fit with the Boltzmann equation. Data are mean ± SEM