Figure 7.

Analysis of atrial action potential waveforms. Intracellular recording of atrial action potential waveforms during regular 6 Hz pacing (A) and their first derivatives reflecting (dV/dt) (B) in (i) untreated cardiomyocytes, (ii) with 8‐CPT challenge followed by (iii) further addition of dantrolene, as well as (iv) dantrolene alone. These recordings yielded values of (dV/dt)_max (C) that could be compared with remaining features of the resting potential (RMP) (D) and APD ₉₀ (E). Single, double and triple symbols denote significantly different pairs of values, to a significance value of P < .05, .01 and .001 respectively