Isoflurane Pretreatment Inhibits Cytokine-induced Cell Death in Cultured Rat Smooth Muscle Cells and Human Endothelial Cells

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Abstract
Background: Anesthetics are protective during ischemic-reperfusion injury and associated inflammation; therefore, the authors hypothesized that anesthetic pretreatment may provide protection in culture from cytokine-induced cell death. Methods: Rat vascular smooth muscle (VSM) cell and human umbilical vascular endothelial cell (HUVEC) cultures were used to determine whether pretreatment with 30 min of isoflurane decreases cell death from tumor necrosis factor alpha (TNF-alpha), interleukin 1 (IL-1 beta), and interferon (IFN-gamma) alone or in combination. Cell survival and viability were determined by trypan blue staining and cell proliferation assay, as well as by DNA fragmentation assays. The roles of protein kinase C (PKC) and adenosine triphosphate-sensitive potassium (K(ATP)) channels in mediating isoflurane (and halothane) protection were evaluated with the antagonists staurosporine or glibenclamide in cytokine- and also hydrogen peroxide (H(2)O(2))-induced cell death. Results: Pretreatment with 1.5% isoflurane immediately prior to cytokine exposure increased cell survival and viability from cytokines by 10-60% for 24, 48, 72, and 96 h in VSMs and up to 72 h in HUVECs. DNA fragmentation (TUNEL) was also attenuated by isoflurane. Isoflurane was equally effective in VSMs at 0.75, 1.5, and 2.5%, whereas in HUVECs, 1.5 and 2.5% were more effective than 0.75%. In VSMs, isoflurane administered 1 h prior to or simultaneously with cytokines was also effective, whereas isoflurane 2 h prior to cytokines was less effective, and either 4 h prior to or 30 min after cytokines was not effective. In both cytokine- and H(2)O(2)-induced cell death, isoflurane and halothane pretreatment were equally protective, and staurosporine and glibenclamide attenuated the protective effect. Conclusions: Thirty minutes of isoflurane attenuates cytokine-induced cell death and increases cell viability in VSMs for 96 h and in HUVECs for 72 h. Isoflurane must be administered less than 2 h prior to or simultaneously with the cytokines to be protective. These initial inhibitor studies suggest involvement of PKC and K(ATP) channels in isoflurane and halothane protection against both cytokine- and H(2)O(2)-induced cell death of VSMs and HUVECs.