Fig. 2.
Propofol dose dependently and exposure time dependently increases the number of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate in situ nick end labeling (TUNEL)–positive cells. (A) TUNEL staining was used to identify damaged DNA and assess cell death following a single exposure to 6 h of various doses of propofol. Hoechst 33342 was used to stain the nuclei that are shown in blue. Most of the TUNEL-positive staining (red) was localized to the DNA-stained nuclei, and the number of TUNEL-positive cells observed was considerably higher in the 20 μg/ml propofol-treated cells when compared with control cells (a). The TUNEL-positive cells were counted to quantify the data, and cell death was significantly increased after exposure to 20 μg/ml propofol but not after exposure to either 5 or 10 μg/ml propofol (b). (B) TUNEL staining was also used to assess cell death following three, 6-h exposures to various doses of propofol. The number of TUNEL-positive cells appeared to be much greater in the 10 and 20 μg/ml propofol-treated cells when compared with control (a). To quantify the results, the number of TUNEL-positive cells was manually counted and we found that cell death was significantly increased in both the 10 μg/ml and 20 μg/ml propofol-treated groups when compared with control but not in the 5 μg/ml propfol-treated group (b). *P < 0.05 and **P < 0.01 versus respective control, n = 3/group.