Acidification prevents endothelial cell apoptosis by Axl activation.

Prior studies have shown that acidification due to hypercarbia protects endothelial cells from serum deprivation-induced apoptosis. However, the mechanism(s) responsible for the antiapoptotic effect of acidification is still unclear. cDNA array screening was performed on human umbilical vein endothelial cells cultured in a bicarbonate medium equilibrated either with 5% CO2 (pH 7.4) or with 20% CO2 (pH 7.0). Tyrosine kinase receptor Axl expression was 3.3-fold higher after 6 hours at pH 7.0 compared with pH 7.4; this modulation was confirmed by reverse transcriptase-polymerase chain reaction (3.0+/-0.9-fold, P