Emulsified isoflurane pretreatment attenuates myocardial ischemia-reperfusion injuries by suppressing toll-like Receptor-4.

Objective: This study aimed to investigate the mechanism of emulsified isoflurane in reducing myocardial ischemia-reperfusion injury (MIRI).

Materials and methods: Forty-eight healthy male Sprague-Dawley rats were randomly divided into four groups (n = 12). In the sham group (group S) and ischemia-reperfusion group (group I/R), saline (4 ml/kg/h) was administered intravenously for 30 min. In intralipid group (group L), intralipid (4 ml/kg/h) was administered intravenously. In the emulsified isoflurane group (group EI), emulsified isoflurane (4 ml/kg/h) was administered intravenously. The infusion was then discontinued for 15 min during the washout period. Apart from group S, ischemia was produced by occlusion of the left anterior descending artery (LADA) for 30 min. After 30 min of occlusion, all groups received reperfusion for two hours.

Results: Creatine kinase MB (CK-MB), cardiac troponin I (cTnI), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) were measured by enzyme-linked immunosorbent assay (ELISA). Myocardial infarct size was measured using triphenyl tetrazolium chloride staining. According to the result, pretreatment with emulsified isoflurane attenuated CK-MB and cTnI concentrations (p < 0.05). And serum TNF-α and IL-6 levels and infarct size in the emulsified isoflurane group obviously decreased. An obvious decrease in the expression of the toll-like receptor-4 (TLR-4) mRNA in group EI was observed compared with group I/R.

Discussion and conclusion: Emulsified isoflurane precondition had a potent cardioprotective effect against myocardial ischemia-reperfusion injury. The mechanisms involved may be related to the decrease in the expression of TLR-4 and the reduced inflammatory response.