['Phospholamban (PLB) regulates the cardiac Ca', 'Using confocal immunofluorescence microscopy and immunoblot analyses of CMs and CM nuclei, we discovered that PLB was highly concentrated in NE. Moreover, the ratio of PLB levels to SERCA levels was greater in NE than in SR. The increased levels of PLB in NE were a consistent finding using a range of antibodies, tissue samples, and species. To address a possible role in affecting Ca'] Is phospholamban concentrated in the nuclear envelope of cardiomyocytes and involved in perinuclear/nuclear calcium handling?