Figure 2
p.P888L SAP97 slows the Ito,f inactivation process. (a) Outward currents elicited by 500-ms pulses to +50 mV in Sham, WT-SAP97 and p.P888L-SAP97 cardiomyocytes. (b-e) Peak Ito,f density-voltage (b), Ito,f charge density-voltage (c), activation (d) and inactivation (e) curves obtained in cardiomyocytes from the three mouse groups. (f) Ito,f reactivation kinetics measured by a double-pulse protocol (top). Continuous lines represent the Boltzmann (d-e) and the monoexponential or biexponential fits (f), respectively, to the datapoints. In b-f each point represents the mean ± SEM of “n” experiments/cardiomyocytes dissociated from five mice of each group. (g) K+ current traces elicited by 4-s pulses in WT-SAP97 and p.P888L-SAP97 cardiomyocytes. (h) Density of the fast and slow components derived from the biexponential fit to the decline of the currents elicited by 4-s pulses to +50 mV in WT-SAP97 and p.P888L-SAP97 cardiomyocytes. (i) Fast and slow time constants of inactivation obtained by fitting a biexponential function to the K+ current traces elicited by 4-s pulses in WT-SAP97 and p.P888L-SAP97 cardiomyocytes. (j) K+ current traces elicited by 4-s pulses in WT-SAP97 and p.P888L-SAP97 cardiomyocytes in the presence of 25 mM TEA. (k) Density of the fast component derived from the monoexponential fit to the decline of the currents elicited by 4-s pulses to +50 mV in WT-SAP97 and p.P888L-SAP97 cardiomyocytes in the presence of 25 mM TEA. (l) Inactivation time constants obtained by fitting a monoexponential function to the K+ current traces elicited by 4-s pulses in WT-SAP97 and p.P888L-SAP97 cardiomyocytes in the presence of 25 mM TEA. (m) Ito,f charge-density generated by 4-s pulses to +50 mV in WT-SAP97 and p.P888L-SAP97 cardiomyocytes in the presence of 25 mM TEA. *P < 0.05 vs Sham, #P < 0.05 vs SAP97 WT.
