Dexamethasone (dex)

Corticosteroid rescue was administered at varying intervals according to group at a dose of 0.1 mg/g. Group A received dexamethasone (Sandoz, Boucherville, QC, Canada) at T-1 hour prior to ototoxic administration (Figure 1). Group B had dexamethasone administered at T + 1 hour post furosemide injection, Group C had dexamethasone administered 6 hours post furosemide injection, Group D had dexamethasone administered 12 hours post furosemide injection and Group E had dexamethasone administered 72 hours post furosemide injection. The control group had the ototoxic insult administered but no steroid rescue was given, and served as confirmation of the ototoxicity model. All animals were given 1 cc of normal saline subcutaneously on the first day following the ototoxic insult. Mice were anaesthetized with isoflurane and sacrificed by cervical dislocation at 7 days post-corticosteroid rescue or 7 days after the ototoxin regiment in the control group.

Lipopolysaccharide (LPS) from Pseudomonas aeruginosa was purchased from Sigma-Aldrich (Oakville, ON, Canada) and dissolved in sterile saline (0.9% NaCl) to a concentration of 10 mg/mL prior to storage at −20 °C. HU-308 was purchased from Tocris Bioscience (Toronto, ON, Canada) and dissolved in anhydrous ethanol at 20 mg/mL prior to preparation in 1:1:18 solution of HU-308: Kolliphor EL: sterile saline and stored at 4 °C. Dexamethasone (Sandoz; Basel, Switzerland) was dissolved in sterile saline to a concentration of 33.3 µg/mL and stored at room temperature. Albumin-fluorescein isothiocyanate (FITC-albumin; λEX = 450–490 nm; Sigma-Aldrich) was dissolved in sterile saline to 50 mg/mL. Rhodamine-6G (λEX = 515–560 nm; Sigma-Aldrich) was dissolved in sterile saline to 0.5 mg/mL. Sodium pentobarbital (240 mg/mL; BimedaMTC Animal Health Inc.; Cambridge, ON, Canada) was diluted with sterile saline and used to provide anesthesia or euthanasia, where applicable. Isoflurane USP (99.9%; Fresenius Kabi; Bad Homburg, Germany) was used to provide inhalant anesthesia for lung intravital experiments only.