Figure 2.

Effects of Disopyramide on Intracellular Ca²⁺

(A) Representative intracellular Ca²⁺ traces recorded during regular stimulation at 0.2, 0.5, and 1 Hz, in the absence (left, black) and presence of disopyramide 5 μmol/l (Diso) (blue traces on the right). (B) Percentage of variation of diastolic [Ca²⁺]_i, and Ca-transient amplitude (Systolic Ampl) with the application of disopyramide 5 μmol/l with respect to baseline in hypertrophic cardiomyopathy cardiomyocytes, during regular stimulation at 0.2, 0.5, and 1 Hz at steady state. (C) Representative superimposed action potentials (top) and simultaneously recorded Ca transients (bottom) at baseline (black traces) and in the presence of disopyramide (blue traces), elicited at 0.2 Hz (left) and 0.5 Hz (right). (D) Time from peak to 50% decay of Ca transients at baseline (black) and in the presence of disopyramide 5 μmol/l (blue), elicited at 0.2, 0.5, and 1 Hz. (B to D) Mean ± SEM from 26 cardiomyocytes from 7 patients with hypertrophic cardiomyopathy (ID# 5 to 9 and 11 to 13). *0.05 > p > 0.01; **0.01 > p > 0.001; linear-mixed models. MP = membrane potential.