Abstract: Objective The purpose of this study was to investigate the effects of epidural ropivacaine block combined with propofol intravenous anesthesia on CaMKII and ERK1/2 total protein (T-CaMKII and T-ERK1/2) and phosphorylation (p-CaMKII and p-ERK1/2) levels in the hippocampus and cortex of rats. Methods Rats were randomly assigned to three groups: group P(control， propofol intravenous anesthesia)、group PS( propofol and epidural normal saline) and group PR( propofol and epidural 0.5% ropivacaine). There were 8 rats in each group. Anesthesia were performed in 72 h after epidural catheter placement． The rats in group PR received 70 μL of 0.5% ropivacaine to achieve epidural block．1% propofol was infused through rats caudal vein. Propofol dosage for anesthesia induction was 12 mg/kg, for anesthesia maintenance was 40 mg/kg/h. Before the rats were decapitated,the depth of anaesthesia was assessed as either “light anesthesia” or “deep anesthesia” by checking of pinch withdrawal reflex, eyelid reflex and spontaneous rapid whisking of the vibrissae after propofol continuous infusion for 1 h. T-CaMKII/T-ERK1/2 and p-CaMKII/p-ERK1/2 in hippocampus and frontal cortex were examined by Western blot. Results 7 rats were assessed as “light anesthesia” and 1rat as “deep anesthesia” in group P; 6 rats were assessed as “light anesthesia” and 2 rats as “deep anesthesia” in group PS; In group PR, 1 rat was assessed as “light anesthesia” and 7 rats as “deep anesthesia”. Significant differences were seen among three groups (P<0.05). In hippocampus of rats, p-CaMKII(Thr286)(43.7±8.8)% and p-ERK1/2(32.4±7.9)% in group PR were significantly lower than those in group P (100%, P<0.05). Conclusions Epidural ropivacaine block could strengthen the depth of anesthesia achieved with propofol intravenous anesthesia. The decrease of the levels of p-CaMKII(Thr286) and p-ERK1/2 in hippocampus of rats may participate in the effects of epidural block.

Key words: Propofol, Epidural block, CaMKII, ERK1/2