Letter to the Editor

In their study recently published inThe Journal of Physiology, Lipsettet al.(2019) attempted to explain t-tubulardefects observed in pathological cardiacremodelling during heart failure (HF) asthe result of reactivation of the fetal geneprogramme in cardiomyocytes. In fact,fetal cardiomyocytes show rudimentaryt-tubular architecture, structurally similarto t-tubules of HF cardiomyocytes. Theauthors observed that fetal t-tubules arefunctional while t-tubules of HF cardio-myocytes show defective triggering of localCa2+release. This work suggests thatreactivation of the fetal gene programmeis partly responsible for HF remodellingbut cannot completely explain t-tubulefunctional defects in HF cardiomyocytes.