TMDJ-035 is a selective inhibitor of the RyR2 (ryanodine receptor 2). It effectively suppresses abnormal calcium (Ca^2+) waves and transients in isolated cardiomyocytes derived from mice with RyR2 mutations. As such, TMDJ-035 serves as a valuable tool in research for elucidating the gating mechanisms and dynamics of the RyR2 channel [1].