1d). Concentration of lidocaine, bupivacaine and ropivacaine has a significant effect on cell death (for lidocaine P < 0·001, bupivacaine P < 0·001 and ropivacaine P = 0·001). Group arrangement also influences cell survival significantly: P = 0·001 for lidocaine, P = 0·029 for bupivacaine and P = 0·01 for ropivacaine.
Cell viability determined in fibroblasts from group 1 showed a similar pattern to trypan blue assays: only minor impairment over time was observed for the three Ceritinib concentration LA with the 0·3 mg/ml concentration (Fig. 2a). While viability was not diminished after incubation with lidocaine and ropivacaine at a 0·6 mg/ml concentration, MTT decreased time-dependently after incubation with bupivacaine (Fig. 2b). In group 2, MTT did not change upon incubation with lidocaine and ropivacaine with the lower concentration. However, no cells survived after 9 days of bupivacaine exposure (Fig. 2c). With the higher concentration, fibroblasts experienced serious impairment of viability with increasing exposure time. The most pronounced effect was observed in the bupivacaine group (Fig. 2d). Correlation analysis revealed a time- and concentration-dependent effect on cell viability for all three LA with the following values: lidocaine time P = 0·019, concentration P < 0·001; bupivacaine time P = 0·05, concentration P < 0·001; ropivacaine time P = 0·004, concentration P < 0·001. An effect based on the type
of stimulation (group 1 or 2) was not observed. Thymidine incorporation over time upon incubation HM781-36B cell line with each of the three LA was not changed after exposure to a low concentration of LA (Fig. 3a). With the 0·6 mg/ml concentration, again the proliferation rate was decreased only in the bupivacaine not group (Fig. 3b). In group 2, with continued incubation with the low LA concentration, the proliferation rate decreased to 80% in the lidocaine and ropivacaine groups (Fig. 3c). This effect
was more pronounced with the 0·6 mg/l concentration. Bupivacaine had a more pronounced effect on thymidine incorporation with both concentrations compared to the two other LA (Fig. 3d). LA concentration had a statistically significant impact on proliferation rate (lidocaine: P < 0·001, bupivacaine: P < 0·001, ropivacaine P = 0·001), as did the group constellation (lidocaine: P < 0·001, bupivacaine: P = 0·009, ropivacaine P = 0·001). Fibroblast apoptosis was determined upon exposure to lidocaine, bupivacaine and ropivacaine. In group 1, apoptosis rate was diminished for all three LA in a similar manner for both concentrations (Fig. 4a and b). With permanent incubation with LA, the apoptosis rate decreased in a time- and concentration-dependent fashion for lidocaine. An increase in the apoptosis rate was observed at 3 days of incubation with the 0·3 mg/ml (bupivacaine, ropivacaine) and 0·6 mg/ml (ropivacaine) concentrations (Fig. 4c and d).