Background
The therapeutic effects of Qiliqiangxin capsule (QLQX), a Chinese patent medicine, in patients with chronic heart failure are well established. However, whether QLQX modulates cardiac calcium (Ca2+) signals, which are crucial for the heart function, remains unclear.
Conclusions
Our findings provide the first line of evidence that QLQX directly modulates cardiac Ca2+ signals in a human cardiomyocyte model.
Methods
Fluorescence imaging was used to monitor Ca2+ signals in the cytosol and nuclei of hiPSC-CMs. For Ca2+ spark measurements, the line-scan mode of a confocal microscope was used.
Results
The QLQX treatment substantially decreased the frequency of spontaneous Ca2+ transients, whereas the amplitude of Ca2+ transients elicited by electrical stimulation did not change. QLQX increased the Ca2+ spark frequency in both the cytosol and nuclei without changing the sarcoplasmic reticulum Ca2+ content. Interestingly, QLQX ameliorated abnormal Ca2+ transients in CMs differentiated from hiPSCs derived from patients with long-QT syndrome. Conclusions: Our findings provide the first line of evidence that QLQX directly modulates cardiac Ca2+ signals in a human cardiomyocyte model.