The effect of combined administration of cadmium and furosemide on auditory function in the rat

A number of heavy metals have been associated with toxic effects to the per ipheral or central auditory system. These include lead, arsenic, mercury, p latinum and organic tin compounds. In addition, the ototoxic effects of som e metals may be potentiated by other factors. However, the auditory effects of cadmium have not previously been reported. The purpose of the present s tudy was to investigate the potential ototoxic effects of cadmium from an a cute dosage, and its potentiation by furosemide. Auditory brainstem respons e (ABR) thresholds were measured in adult Sprague-Dawley rats. Rats receive d either cadmium chloride (5 mg/kg, i.p.) followed by saline (4 ml/kg, i.p. ), cadmium chloride followed by furosemide (200 mg/kg, i.p.), or furosemide alone. Follow-up ABRs were carried out 7 days post-treatment and threshold changes were compared between each treatment group. No significant thresho ld change was seen for the cadmium chloride plus saline treated or the furo semide treated animals. However, significant threshold elevations were obse rved in animals receiving cadmium chloride plus furosemide. In addition, sc anning electron microscopy revealed extensive hair cell loss in animals tre ated with cadmium chloride and furosemide. Although functional auditory cha nges were not seen after the administration of cadmium alone, the potentiat ion of threshold changes by furosemide suggests that cadmium may be ototoxi c under certain conditions. (C) 1999 Elsevier Science B.V. All rights reser ved.