RESUMEN
AIM: Our study is to determine the influence of ropivacaine-loaded magnetic nanoparticles (MNP/Rop) on ankle nerve block in rats. MATERIALS AND METHODS: MNP/Rop was prepared and then injected intravenously into rats to evaluate its anesthetic effect on rat limbs. Mechanical pain thresholds paw withdrawal threshold (PWT) and paw withdrawal thermal latency (PWL) were employed for the assessment of ankle nerve block in rats. RESULTS: PWT increased from T1 to T4 in each group (P < 0.05). The intergroup comparison determined no distinct difference in the PWT value among the three series at T1 (P > 0.05); however, PWT values at T2-T4 were higher in nerve block control group (NBCG) and MNP/Rop group than in blank group (BG), and they remained slightly higher in MNP/Rop group than in NBCG. The intragroup comparison revealed that from T1 to T4, PWL in each group showed a rising trend. The PWL at T1 showed no evident difference among the three series (P > 0.05); however, PWL values at T2-T4 were higher in NBCG and MNP/Rop group than in BG, and they remained slightly higher in MNP/Rop group than in NBCG. In MNP/Rop group, both PWT and PWL increased with the increase of Fe3O4 load in MNP/Rop (P < 0.05), while PWT and PWL remained unchanged when the load was 2.189%; moreover, PWT and PWL elevated as Rop concentration increased in MNP/Rop (P < 0.05), while they kept unaltered under 40 µL 1% Rop. CONCLUSION: Intravenous injection of MNP/Rop into rats and inhalation of MNP into the ankle joint can effectively block ankle nerve conduction in rats.