title: A correlation of the effects of normoxia, hyperoxia and anoxia on PO2 of endolymph and cochlear potentials.
abstract: Change in PO2 in endolymph, endocochlear potentials and cochlear microphonics have been tested in normoxia, hyperoxia and anoxia on 24 guinea pigs. The polarographic method and construction of oxygen-sensitive microelectrodes is described in detail. The normal level of PO2 in endolymph vaires between 20 and 30 mm Hg. One-minute anoxia induced by breathing 100% N2 caused a decline in PO2, EP and CM, but during recovery only PO2 returned with over-correction to the preexposure level. Hyperoxia evoked by breathing 100% oxygen failed to increase the cochlear potentials and the PO2 in the endolymph. This suggests that vasoconstriction most likely occurs proximal to the capillaries bed of the stria vascularis.
mesh_terms: D000818:Animals; D003051:Cochlea / Q000502:physiology*; D003055:Cochlear Microphonic Potentials; D004710:Endolymph / Q000378:metabolism*; D005072:Evoked Potentials, Auditory; D006168:Guinea Pigs; D007761:Labyrinthine Fluids / Q000378:metabolism*; D010101:Oxygen Consumption; D012119:Respiration