Figure 5. AP prolongation facilitated Ca²⁺ entry in 7-week KO.

A, representative AP recordings at 1 Hz. B, times to 20%, 50% and 70% repolarization (APD₂₀, APD₅₀ and APD₇₀) (n= 16, 17, 11, 16; *P < 0.05 vs. corresponding FF). C, representative Ca²⁺ transients recorded during voltage-clamp stimulation with AP waveforms from A. Insets illustrate an expanded time scale with APs superimposed. Transient magnitude (D), integrated L-type Ca²⁺ current (E), and decay kinetics of the Ca²⁺ transient (F). (n for panels D, E and F: 7-week FF = 9, 8, 9; 7-week KO = 12, 4, 12; *P < 0.05 vs. equivalent FF AP, ‡P < 0.05 vs. equivalent 7-week FF).