title: Mechanism of lack of development of negative endocochlear potential in guinea pigs with hair cell loss.
abstract: The endocochlear potential (EP), and the concentration of K+, Na+ and Cl- were measured simultaneously in endolymph of guinea pigs. The EP was 85.6 +/- 0.8 mV in normal guinea pigs, 90.7 +/- 0.8 mV in the kanamycin-treated animals, and 91.6 +/- 1.2 mV in those treated with nitrogen mustard-N-oxide (NMNO). Thirty minutes after the onset of anoxia, the EP (negative EP) was -29.3 +/- 1.0 mV in the normal group, -0.2 +/- 1.0 mV in the kanamycin-treated group, and -1.9 +/- 1.3 mV in the NMNO-treated group. The permeability coefficients of K+ (Pk), Na+ (Pna) and Cl- (Pcl) across the endolymph-perilymph barrier during the period of 20-30 min after the onset of anoxia in the normal group were (341.6 +/- 38.2) x 10(-9) cm3 sec-1, (53.0 +/- 8.1) x 10(-9) cm3 sec-1 and (111.8 +/- 27.2) x 10(-9) cm3 sec-1, respectively. Pk was decreased in the kanamycin- and NMNO-treated groups. Pna did not differ between the normal and treated groups. Pcl was increased in the kanamycin- and NMNO-treated groups. The K+:Na+:Cl- permeability ratio was 1:0.16:0.32 in the normal group, 1:1.12:11.6 in the kanamycin-treated group, and 1:0.44:5.60 in the NMNO-treated group. The results indicate that the lack of development of a negative EP in the kanamycin- and NMNO-treated guinea pigs was attributable to the increased Pcl and the decreased Pk across the endolymph-perilymph barrier, probably the organ of Corti, during anoxia.
authors.affiliation: Department of Otorhinolaryngology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Komune
authors.forename: T
authors.initials: T
authors.lastname: Nakagawa
authors.forename: K
authors.initials: K
authors.lastname: Hisashi
authors.forename: T
authors.initials: T
authors.lastname: Kimitsuki
authors.forename: T
authors.initials: T
authors.lastname: Uemura
mesh_terms: D000818:Animals; D002712:Chlorides / Q000378:metabolism*; D003051:Cochlea / Q000187:drug effects / Q000502:physiology; D004710:Endolymph / Q000378:metabolism; D005072:Evoked Potentials, Auditory / Q000187:drug effects / Q000502:physiology*; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000187:drug effects / Q000502:physiology*; D007612:Kanamycin / Q000633:toxicity; D008466:Mechlorethamine / Q000633:toxicity; D010498:Perilymph / Q000378:metabolism; D010539:Permeability; D011188:Potassium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*
chemical_list: D002712:Chlorides; D008466:Mechlorethamine; D007612:Kanamycin; D012964:Sodium; D011188:Potassium