[Effects of intravenous anesthetics on acidosis induced apoptosis in primary brain cell culture].

Background: We have reported protective effects of intravenous anesthetics on the brain cell. This study examined the effects of extracellular Ca2+ on acidosis-induced apoptosis and the protective effects of intravenous anesthetics on such appearance of apoptosis.

Methods: Using the primary culture of rat cerebellular granule cells, extracellular acidosis was produced at pH 6.7 and pH 6.3 and the extracellular Ca2+ free condition was produced by 1 mM EGTA instead of 1.2 mM CaCl2. The cell death was determined by the calcein method and the measurement of apoptosis was done using the screening kit for apoptosis with TUNEL method. Bcl-2 mRNA was detected using quantified RT-PCR method. Midazolam, pentobarbital and propofol were used as typical intravenous anesthetics.

Results: Under extracellular acidosis, the significant cell death was detected 6 hr after exposure to acidosis. Moreover, in case of extracellular Ca2+ free/acidosis condition, there was a greater incidence of cell death. Such cell death was much enhanced 20 hr after exposure to acidosis. Furthermore, in case of extracellular acidosis and Ca2+ free condition, there were a significant increase of apoptosis and significant changes of bcl-2. By treatment with intravenous anesthetics, the significant inhibition of cell death and appearance of apoptosis were observed. In these protections by intravenous anesthetics, midazolam and pentobarbital significantly increased the bcl-2 levels.

Conclusions: We demonstrated that intracellular Ca2+ modulates the appearance of apoptosis under acidosis. Moreover it seems that the inhibitory effects of midazolam and pentobarbital on acidosis-induced apoptosis are different from that of propofol.