Study Of The Anti-inflammatory Effects Of Ketamine

Objective Ketamine, a phencyclidine derivatives,has been advocated for anesthesia and analgesia of septic patients because of its ability to stabilize the cardiovascular function during sepsis. Recently, some studies showed that ketamine had a significant anti-inflammatory effect. But the mechanisms are not clear, and the inhibitory effect of ketamine on the endothelial cells activation is still under debate. Therefore, in this study, we investigated the influence of different concentrations of ketamine(12.5, 25, 100 and 300 n mol/L) on the expression of intercellular adhesion molecule-1 (1CAM-l)and the translocation of NF- K. B into nuclei of human umbilical vein endothelial cells(HUVECs). The effect of ketamine on the expression of CDllb and neutrophils-endothelium adhesion rate with relevance inflammation were also examined.Methods HUVECs were enzymatically isolated and cultured in RPMI1640 culture medium at 37 C for about 10 days when a monolayer of endothelial cells has grown. The cultured HUVECs were stimulated with LPS(lipopo]ysaccharide) 1 u g/ml for 18 hours in the absence or prescence of ketamine(12.5, 25, 100 and 300 w mol/L). Subsequently, the HUVECs were harvested for flow cytometric analysis of ICAM-1. In another set of experiments, the cultured HUVECs were stimulated with LPS 1 y g/ml for 2 hours in the absence or prescence of ketamine(12.5, 25, 100 and 300 u mol/L). The translocation of NF-*B into nuclei was stained with immunohistochemistry technique.The neutrophils were isolated using a Percoll-Ficoll method. Fresh isolated neutrophils were incubated with FMLP(formyl-methionyl-leucyl-phenylalanine) 10-6mol/L for 20 minutes in the absence or prescence of ketamine(12.5, 25, 100 and 300 u mol/L). Subsequently, the neutrophils were collected for flow cytometric analysis of CDllb. In another set of experiments, the activatedneutrophils were placed on the surface of HUVECs, and the adhesion rates of neutrophils to endothelial cell were detected using gentiavern staining.Result There was slight expression of ICAM-l(mean fluorescence intensity 7.91 + 1.37) on the surface of HUVECs in normal condition. Stimulation of the cells with LPS(1 y g/ml) for 18h considerably increased ICAM-1 expression to 50.45 +3.45. At 25, 100 and 300ymol/L, ketamine significantly reduced this increase(P<0.05). After incubated with LPS(1 y g/ml) for 2h, the translocation of NF- K B was upregulated about 5-fold to 61.90+1.69. 5=25 y mol/L ketamine significantly inhibit the translocation of NF- K B into nuclei(P<0.05), and the inhibitory effect of ketamine on the expression of ICAM-1 and the translocation of NF-KB displayed positive correlation (r=0.985, PO.01). MK-801 had no effect on the expression of ICAM-1 and the translocation of NF- K B.The coincubation of neutrophils with FMLP(10"6mol/L) led to chemotactic activation of the neutrophils, which showed as an upregulation of CDllb and adhesion rate of neutrophils to endothelium. All concentration we used of ketamine significantly reduced those increase, and displayed positive correlation(r=0.987, P<0.01). No concentration test did MK-801 have an effect on the stimulated of neutrophils.Conclusion Ketamine could inhibit the FMLP induced neutrophils reactivity. At the higher concentration(> 25 u mol/L), ketamine could suppressed LPS induced HUVECs activation. The inhibitory effects of ketamine is most likely not mediated through NMDA receptor interactions. These dates showed that ketamine suppressed the inflammatory reaction, in part, via the inhibition of NF- K B translocation.