Effects of ascorbic acid on etomidate-induced inhibition of adrenocortical function in rabbits

Objective: To investigate the effect of ascorbic acid (AC) on the etomidate (ETO)-induced inhibition of adrenocortical function. Methods: The rabbits were randomly divided into the etomidate (ETO), ETO+AC1 [ETO+AC (275 mg/kg)] and ETO+AC2 [ETO+AC (550 mg/kg)] groups. The rabbits were anaesthetised by ear vein injection of ETO (1.0 mg/kg), and the anaesthesia was maintained by three ear vein injections of ETO (0.6 mg/kg/h) for 30 min once a week to induce the inhibition of adrenocortical function. The rabbits were injected with AC (275 or 550 mg/kg) by ear vein 20 min before the injection of ETO. Venous blood was sampled by the ear vein from each rabbit at 0, 2 and 6 h after final injection of ETO. The serum cortisol and adrenocorticotropic hormone (ACTH) levels were detected by enzyme-linked immunosorbent assay (ELISA). Results: Compared with the ETO group, serum cortisol levels in the ETO+AC1 and ETO+AC2 groups were significantly increased dose-dependently (all P<0.05). Compared with that measured at 0 h, serum cortisol levels in ETO+AC1 and ETO+AC2 groups at 2 and 6 h were significantly increased (all P<0.05). Compared with the ETO group, the variance ratios of serum cortisol concentration in the ETO+AC1 and ETO+AC2 groups at 2 and 6 h were significantly increased (all P<0.05). Compared with that at 2 h, the variance ratios of serum cortisol concentration in the ETO+AC1 and ETO+AC2 groups at 6 h were significantly increased (all P<0.05). Compared with the ETO group, serum ACTH levels in the ETO+AC1 and ETO+AC2 groups at 0, 2 and 6 h were significantly decreased dose-dependently (all P<0.05). Compared with that at 0 h, serum ACTH levels in the ETO+AC1 and ETO+AC2 group at 2 and 6 h were significantly decreased (all P<0.05). Compared with that in the ETO group, serum ACTH levels in the ETO+AC1 and ETO+AC2 groups at 6 h were significantly increased (all P<0.05). Compared with the levels at 2 h, serum ACTH levels in the three groups at 6 h were significantly increased (all P<0.05). Conclusions: Pretreatment with AC suppresses the ETO-induced inhibition of adrenocortical function in rabbits.