THE CALIBRATION OF S-35 LABELED OR P-32 LABELED WITH C-14-LABELED BRAIN PASTE OR C-14 PLASTIC STANDARDS FOR QUANTITATIVE AUTORADIOGRAPHY USING LKB ULTROFILM OR AMERSHAM HYPERFILM

The relationship between C-14-labeled brain paste or plastic standards and S-35- or P-32-labeled brain paste was characterized with quantitative autoradiography. Film was exposed to both sets of C-14-labeled standards and S-35-and 32-P-labeled standards for 15-148 h and the film was analyzed with computer densitometry. Subsequently, the tissue pastes were scraped from the slides, dissolved in tissue solubilizer and radioactivity determined by scintillation spectroscopy. A linear relationship was observed between the plastic and brain paste C-14 standards as well as between both sets of C-14-labeled standards and S-35-labeled brain paste standards. The 32-P-labeled standards demonstrated a poor linear relationship with the C-14-labeled standards and greater variability in the autoradiographic estimates than was seen with S-35 or C-14. Results were similar for both Ultrofilm and Hyperfilm with all the radioisotopes. These findings demonstrate a simple linear relationship between plastic and brain paste C-14-labeled standards and between either C-14-labeled standards and S-35-labeled brain paste for use in quantitative autoradiography.