Tios of HPLC peak areas and ratios from PQ7 and BTA concentrations were plotted, and a linear correlation line was obtained from the graph. Hence using this correlation diagram, the ratio of HPLC peak areas of PQ7 and BTA from tissue extract, and the added known amount of BTA to the tissue extract, the amount of PQ7 in the tissue extract was determined.Hence, 100 of 1:1 mixture by volume of the tissue or plasma extract and BTA of known concentration was injected into the HPLC, the peaks corresponding to PQ7 and BTA were integrated from the HPLC chromatogram, and the ratio 10457188 of their masses was determined. Comparing the ratio of the masses of the peaks of PQ7 in the extract and standard BTA to the ratio of the masses of the peaks of authentic PQ7 and standard BTA, the mass of PQ7 in the organs and plasma was quantified. Mass Spectroscopy. An Applied Biosystem API 2000 LS/MS/MS mass spectrometer was used in the analysis. The eluent corresponding to PQ7 peak from the HPLC was collected and injected into the mass spectrometer. A mass of 406 corresponding to M+1 of PQ7 was found in the mass spectrum, and the fragmentation pattern of this M+1 mass is similar to that of the authentic PQ7 verifying the identity of PQ7. Antibodies. Primary antibodies: Anti-Cx46 (sc-20859, goat polyclonal), anti-PKC (sc-8393, mouse monoclonal), and anti-Cx43 (sc-13558, mouse monoclonal), from Santa Cruz Biotechnology (Santa Cruz, CA); anti-GAPDH (2118, rabbit monoclonal) from Cell Signaling (Boston, MA) were used for both western blot and immunohistochemistry (IHC). Western Blot Analysis. Mammary gland tumor tissue and selected organs (heart, lung, liver, spleen,kidney, uterus, brain) were homogenized in 500 mL of lysis buffer (20 mM Tris pH 7.5, 0.5 mM EDTA, 0.5 mM EGTA, 0.5 Triton X-100) with 1:1,000 dilution of protease inhibitors (Sigma-Aldrich, Saint Louis, MO). Tissue was homogenized via the OMNI Bead Ruptor 24 (Omni International, Kennesaw, GA) at a speed of 5.65 m/s for 45 seconds, followed by centrifugation at 13,000 rpm for 30 minutes at 4 . Twenty-five of whole-cell extract was resolved by 10 SDS polyacrylamide gel electrophoresis (PAGE) and transferred to nitrocellulose membrane (Midwest Scientific, Saint Louis, MO). Nitrocellulose membrane was blocked in 5 milk for an hour at room temperature and then incubated with monoclonal antibodies (1:1,000). Western blots were detected by enhanced chemiluminescence detection reagents (Pierce, Rockford, IL) and visualized by Fluorochem E imaging system (ProteinSimple, Santa Clara, CA). Immunohistochemistry (IHC). Mammary carcinomas and organs were removed and fixed in a solution of 10 formaldehyde and embedded into paraffin prior to sectioning onto slides at a 5 thickness. Paraffin sections (5 ) were dried at 60 for 25 minutes. Deparaffinization was performed in solutions of 100 xylene and 100 , 90 , 75 , 50 ethanol. Antigen retrieval was performed in a steam chamber with 1?citrate buffer solution. Slides were then incubated overnight at room temperature with a polyclonal antibody (1:50 dilution). After washing in PBS, slides were successively incubated with biotinylated secondary antibodies (1:1,000) for 15 minutes. Slides were washed and immunostains were amplified by incubation with Avidin Biotin Complex (ABC) for 10 minutes. Cells were visualized with 3,3diaminobenzidine (DAB) followed by a hematoxylin counterstain. The sections were viewed and the images captured with a Nikon 80i microscope und.