Fig. 6. Influence of protein kinase C (PKC) down-regulation on isoflurane-increased phosphorylated ERK1/2 level. PDBu = phorbol-12,13-dibutyrate, a PKC activator, at 1 μm; PDBu (48 h) = the cultured cells were treated with PDBu for 48 h to down-regulate PKC; PDBu (30 min) = the cultured cells were treated with PDBu for 30 min to activate PKC; Iso = isoflurane at 3%; pERK1/2 = phosphorylated ERK1/2. Mean ± SD (n = 3–9). pERK1/2 levels are expressed as a percentage of the control (100%). *P < 0.05 compared with control containing vehicle; #P < 0.05 compared with 3% isoflurane; $ P < 0.05 compared with PDBu (48 h). PDBu increased the pERK1/2 level (*, PDBu [30 min]), which was greatly reduced in vascular smooth muscle cells with down-regulated PKC ($, PDBu [48 h]). The isoflurane-increased pERK1/2 level (*, Iso) was completely blocked in vascular smooth muscle cells with down-regulated PKC (#, PDBu [48 h] and Iso).