FIG. 2.

ABR and DPOAE threshold shift across treatments. Guinea pigs (n = 24) were exposed to 3 doses of cisplatin (each of 4 mg/kg i.p.). ABR (A, C) and DPOAE (B, D) were measured 3 days post each cycle (A, B) and 1 month post the final cycle (C, D). After the first dose (solid line) minimal ABR (A) or DPOAE (B) threshold shift was observed for cisplatin-only controls (red circles) or animals with ears treated with either cool water (dark blue squares) or cool ear bar (light blue diamond). After the second dosage (dashed lines) a significant ABR (A) and DPOAE (B) threshold shift was observed for the cisplatin-only animals (red circles), but minimal shift for the cool treated ears (dark blue squares and light blue diamonds). After the third dose (dotted line) a high-frequency shift in ABR (A) and DPOAE (B) threshold was observed for all groups, but smaller in the cooled groups. One month after the final cisplatin treatment threshold shift was significantly lower for ABR (C) and DPOAE (D) for animals undergoing cool treatments (dark blue square = cool water and light blue diamond = cool ear bar) compared to cisplatin only (red circles). No significant differences were observed between the two cooling methods. Error bars show standard error of the mean (SEM). ABR indicates auditory brainstem response; DPOAE, distortion product otoacoustic emissions.