Figure 3: PTPIP51 increased mitochondrial and decreased cytosolic Ca²⁺ in cardiomyocytes.

(A) Confocal images of rat neonatal cardiomyocytes immunostained with a rabbit-anti-PTPIP51 antibody and mouse-anti-Tom20, and distribution curves of immunofluorescent intensities (right). Scale bar: 10 μm in merge, and 5 μm in Zoom. (B) Confocal images and representative recordings of mitochondrial Ca²⁺ in rhod-2 AM-loaded neonatal cardiomyocytes transfected with Ad-PTPIP51 or Ad-lacZ in response to 10 μM caffeine stimulation. n = 41–42 cells in each group from five independent experiments. (C) Confocal images and representative recordings of cytosolic Ca²⁺ by Fluo-4 AM fluorescent signal in response to 10 μM caffeine stimulation, in cardiomyocytes transfected with Ad-PTPIP51 or Ad-lacZ. n = 29–31 cells in each group from five independent experiments. *P < 0.05versus Ad-lacZ group. (D) Confocal images and representative recordings of mitochondrial Ca²⁺ and (E) Cytosolic Ca²⁺ in response to 10 μM caffeine stimulation in neonatal cardiomyocytes transfected with PTPIP51 shRNA or scramble shRNA. n = 30–50 cells in each group from three independent experiments in (D) and n = 63–90 cells in each group from five independent experiments in (E). *P < 0.05 versus scramble group. (F & G) Confocal images and representative recordings of cytosolic Ca²⁺ in response to 1 μM FCCP stimulation in neonatal cardiomyocytes transfected with Ad-PTPIP51 (F) or with PTPIP51 shRNA (G). Data are presented as mean ± SEM. Bar charts show quantifications of peak amplitude.