期刊
HEART RHYTHM
卷 14, 期 1, 页码 120-127出版社
ELSEVIER SCIENCE INC
DOI: 10.1016/j.hrthm.2016.10.019
关键词
Calmodulin; Ryanodinereceptor; Sarcoplasmic reticulum; Calcium; Pressure overload
资金
- JSPS KAKENHI [JP15K09085]
- Grants-in-Aid for Scientific Research [16K19409, 15K09085] Funding Source: KAKEN
BACKGROUND Calmodulin (CaM) is a key modulator of the channel gating function of the ryanodine receptor (RyR). OBJECTIVE The purpose of this study was to investigate the pathogenic role of RyR-bound CaM in diastolic Ca2+ leakage from the sarcoplasmic reticulum and arrhythmogenesis in pressure-overloaded heart failure. METHODS Pressure overload was induced in 12-week-old mice by transverse aortic constriction (TAC) using a 27-gauge needle. RESULTS TAC operation for 8 weeks produced a significant increase in left ventricular end-diastolic diameter and frequent occurrence of lethal arrhythmias after infusion of epinephrine and caffeine in TAC mice. The amount of RyR-bound CaM decreased significantly in TAC mice compared with sham mice. The apparent affinity of CaM binding to RyR decreased in pressure-overloaded cells compared with sham cells and untreated cells. High-affinity calmodulin (HA-CaM; ie, CaM whose binding affinity to RyR was significantly increased) restored a normal level of CaM-RyR binding properties in pressure-overloaded cells. HA-CaM corrected abnormally increased Ca2+ spark frequency in the pressure-overloaded cells to the level seen in the sham cells. The frequency of spontaneous Ca2+ transients in TAC cells during and after 15 Hz of field stimulation was 44%, whereas it was significantly attenuated by HA-CaM but not with CaM. CONCLUSION Several disorders in the RyR channel function characteristic of pressure-overloaded cells (increased spontaneous Ca2+ leakage, delayed afterdepolarization, triggered activity, Ca2+ spark frequency, spontaneous Ca2+ transients) are caused by deteriorated CaM binding to RyR2. These disorders could be rectified by restoring normal CaM binding to RyR2.
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