Pyruvate kinase isoenzyme M2 expression correlates with survival of cardiomyocytes after allogeneic rat heterotopic heart transplantation.

The aim of our study was to assess correlations between PKM2 and the survival of cardiomyocytes after heart transplantation in rat. The PKM2, Bcl-xl, active caspase-3 proteins were detected by western blot, and PKM2 was testified by immunohistochemistry and immunofluorescence. At the same time, active caspase-3, α-actinin, VCAM-1, and CD4 were detected by immunofluorescence. Compared with rare expression in syngeneic Lewis rat hearts, the PKM2 protein level in allogeneic hearts was detected at various survival times after transplantation, which prominently expressed on day five postoperatively. In addition, we examined the expression of Bcl-xl and active caspase-3 in allogeneic hearts, which has a similar expression pattern with PKM2. Immunohistochemical and immunofluorescent methods displayed that PKM2 was widely expressed in cardiac tissue, and active caspase-3 was also expressed in cardiomyocytes. However, the PKM2 was not expressed in T cells and other immune response cells. These results suggested that PKM2 may regulate the survival of cardiomyocytes in acute rejection after heart transplantation in rat. Crown