Presence of Heat Shock Protein 72 in Cardiomyocytes After Heat Stress

To the Editor:It is well-known that prior in vivo heat stress induces the synthesis of heat shock protein (HSP) 72 in the rat heart, but the precise content in the various cell-types has not yet been measured. It is therefore of great importance to conduct experiments as performed in the paper by Leger et al. 1 However, the overall conclusion that heat pretreatment does not lead to HSP72 synthesis in cardiomyocytes is unjustified. In addition, the statement that blood vessels play a primary role in the heat shock-induced cardioprotection is preliminary.The double-labeling experiments of Leger et al, 1 staining HSP72, as well as HSP27, clearly indicates the presence of both proteins in the same area, which the authors define as cardiomyocytes in the case of HSP27. Indeed, other studies indicate that cardiomyocytes do overexpress HSP72 after stress: cardiomyocytes of intact hearts are capable of overexpressing HSP72 after heat treatment. 2 Although the increase of HSP72 normalized for protein content was …