Supplementary Figure 5: Electrophysiological characterization of SANLPCs.
(a-c) Analysis of pacemaker funny current densities (If): (a) Current-voltage relationship for If current densities in SANLPCs and VLCMs. (b,c) Representative recordings of funny current (If) in a SANLPC (inset: voltage protocol) made at different membrane potentials in Tyrode’s solution (b) and in the presence of the If blocker Cesium (Cs+) (c) at a concentration of 2 mM. (d) Analysis of acetylcholine activated inward rectifier potassium current densities (IKACh): Current-voltage relationship for IKACh current densities in SANLPCs and VLCMs (inset: voltage protocol). (e) Analysis of sodium current densities (INa): Current-voltage relationship for INa current densities in SANLPCs and VLCMs (inset: voltage protocol). (f,g) Analysis of barium (Ba2+)-sensitive inward rectifier potassium current densities (IK1): (f) Representative recording of the barium sensitive inward rectifier potassium current component in a VLCM (inset: voltage protocol) made at different membrane potentials. (g) Right: Current-voltage relationship for barium-sensitive current densities and left: summary of maximum IK1 current densities recorded at -120 mV in VLCMs and SANLPCs. (h-l) Analysis of outward potassium current densities (IK) and dissection and quantification of the transient outward potassium current (Ito): (h) Representative recording of IK current in a SANLPC and a VLCM (inset: voltage protocol). (i) Peak IK current densities recorded in VLCMs and SANLPCs. (j) Maximum Ito current densities and (k) Ito inactivation time constant determined by curve fitting in VLCMs and SANLPCs. (l) Properties of Ito recovery from inactivation fitted with a bi-exponential function used to separate the fast and slow components of Ito as detailed in the methods. (inset: voltage protocol and parameters of recovery form inactivation determined by curve fitting). All error bars represent s.e.m. t-test: *P < 0.05 **P < 0.01 vs VLCMs.
