Ryanodine Receptor as a New Therapeutic Target of Heart Failure and Lethal Arrhythmia

Abstract

Abnormal intracellular Ca²⁺ handling by the sarcoplasmic reticulum (SR) is a critical factor in the development of heart failure (HF). Not only decreased Ca²⁺ uptake, but also uncoordinated Ca²⁺ release plays a significant role in contractile and relaxation dysfunction. Spontaneous Ca²⁺ release through ryanodine receptor (RyR) 2, a huge tetrameric protein, during diastole leads to a decrease in the SR Ca²⁺ content, and also triggers delayed afterdepolarization that is a substrate for lethal arrhythmia. Several disease-linked mutations of RyR have been reported in patients with catecholaminergic polymorphic ventricular tachycardia (CPVT) or arrhythmogenic right ventricular cardiomyopathy type 2 (ARVC2). The unique distribution of these mutation sites has lead to the concept that an interaction among the putative regulatory domains within RyR may play a key role in regulating channel opening, and that there seems to be a common abnormality in the channel disorder of HF and CPVT/ARVC2. Recent knowledge gained from pathological conditions may lead to the development of a new therapeutic strategy for the treatment of HF or cardiac arrhythmia. (Circ J 2008; 72: 509 - 514)