U46619-induced DNA fragmentation is receptor mediated and inhibited with gentamicin and 2-APB. A. Image of TUNEL positive AVCMs in culture. AVCMs were cultured in the absence of serum for 24 h during treatment with U46619 (0.1-10 μM) or vehicle and then stained with TUNEL (green nuclei) and DAPI (blue nuclei). Cell membranes were pseudo-colored to enhance visualization (red). B. Summary data showing increasing concentrations of U46619 (0.1-10 μM) increased the number TUNEL positive cardiomyocytes when compared to vehicle (n = 4; p < 0.05). *Statistical difference from vehicle. C. Summary data showing that pretreatment with a TXA2R antagonist (SQ29548; 10 μM), IP3 inhibitor (gentamicin, 10 μM), IP3R antagonist (2-APB, 10 μM), or combined IP3 signaling inhibitors (gentamicin + 2-APB) significantly reduced the number of TUNEL positive cardiomyocytes as a result of U46619 (10 μM) treatment (n = 4; p < 0.05). *Statistical difference from 10 μM U46619. Similar results to the TUNEL staining were also found with manual cell counts of viable AVCMs.