title: Variation of distortion product otoacoustic emissions with furosemide injection.
abstract: Cochlear function was monitored in adult gerbils using distortion product otoacoustic emissions (DPOAE) during intraperitoneal injection of furosemide. All stimulus parameters were varied independently over a wide range, the stimulus frequencies f1 and f2 from 1 to 16 kHz, and the stimulus levels L1 and L2 from 20 to 80 dB SPL. The observed emissions at 2f1-f2 and 3f1-2f2 could be considered to be made up of two distinct components: (1) an 'active' source which depended in a complex way on the stimulus frequencies and levels, which was dominant at low and moderate stimulus levels, and which, by definition, was eliminated by sufficient furosemide intoxication; and (2) a 'passive' source which was essentially the same at all frequencies, with a level dependence given approximately by a simple power law distribution. The change from the active to the passive source was usually accompanied by an abrupt shift in emission phase angle. A simple summation model was shown to account for the observed form of this transition. The amount of the decrease in 2f1-f2 emission amplitude after furosemide injection was approximately independent of frequency and consistent for the middle frequency ratios and intensity levels (f2/f1 approximately equal to 1.3, L1 x L2 approximately equal to 55 x 50 dB SPL). It was concluded that the combination of DPOAE with furosemide injection can usefully be employed as a probe of active cochlear mechanics.
authors.affiliation: Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology, Head & Neck Surgery, University of Washington, Seattle 98195.
authors.forename: D M
authors.initials: DM
authors.lastname: Mills
authors.forename: E W
authors.initials: EW
authors.lastname: Rubel
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D003051:Cochlea / Q000187:drug effects / Q000502:physiology; D004594:Electrophysiology; D005665:Furosemide / Q000008:administration & dosage / Q000494:pharmacology*; D005849:Gerbillinae; D007274:Injections, Intraperitoneal; D008954:Models, Biological; D017084:Otoacoustic Emissions, Spontaneous / Q000187:drug effects* / Q000502:physiology
chemical_list: D005665:Furosemide