Figure 5

MMP-9 inhibition prevented Ca²⁺ leakage and irregular calcium transients in hiPSC-CMs.

(A and B) Amplitude and decay of Ca²⁺ transients over time (n = 28–40, from 4 experiments, P = 0.48). (C to H) Summary of Ca²⁺ spark, including the incidence (C), frequency (D), amplitude (E), duration (FDHM, F), and width (FWHM, G), as well as a representative image (H). Ca²⁺ sparks (denoted by white arrows) after treatment with Ang II are prevented by an MMP-9 inhibitor (n = 50–145, from 6 to 8 experiments, ^#P < 0.05 vs. WT + Ang II). (I to K) A summary of irregular Ca²⁺ transients, including their incidence (I) and duration (J), and a representative image (K). Irregular calcium transients were induced only in a high-Ca²⁺ (3.6 mM) Tyrode solution. Irregular, arrhythmia-like calcium transients, denoted by black arrows, were induced after treatment with Ang II and were prevented by MMP-9 or PKA inhibition (n = 33–73, from 3 to 5 experiments, ^#P < 0.05 vs. WT + Ang II). Data are shown as the mean ± SEM.