Cell Death of P19 Embryonal Carcinoma Cells by Intravenous Anesthetics

Objectives: As intravenous anesthetics such as propofol and ketamine are reported to cause cell death, we tested the actions of propofol, pentobarbital and ketamine against P19 embryonal carcinoma (P19EC) cells to examine whether they cause the death of nerve cells. Methods: After P19EC cells were cultured with or without 0.5 µM retinoic acid, various concentrations of those intravenous anesthetics were added to the culture medium. The number of living cells was estimated by measuring the amount of ATP in the cells after 24, 48, and 72 hours. Agarose gel electrophoresis of DNA was done for analyzing the way of the cell death, and lactate dehydrogenase (LDH) and caspase activities were measured. Reactive oxygen species (ROS) and c-jun and c-fos mRNAs were also measured. Results: 1)The decrease in the number of living cells depended on the concentration of intravenous anesthetics added, and correlated with the time lapse after the addition of anesthetics; 2) By treating the cells with retinoic acid, higher concentrations of the anesthetics were necessary to decrease the living cells by 50% 24 hours after their addition, which suggested that the actions of the anesthetics to cause cell death were weakened as P19EC cells differentiated into the nerve cells by treatment with retinoic acid; 3)Ladder formation was observed in DNA electrophoretic pattern after exposure to any of the anesthetics; 4) Caspase activity increased whereas LDH activity did not change. From these, the way of cell death was presumed to be apoptosis. Additionally, since there was no significant change in ROS, c-jun or c-fos level, we presume that the apoptosis occurred by way of a different signal pathway. Conclusions: Propofol, pentobarbital, and ketamine caused apoptosis of P19EC cells and the actions of the anesthetics were weakened by differentiation of P19EC cells to nerve cells.