Cochlear action potentials threshold and systemic arterial pO2.
A progressive decrease in arterial pO2 was induced in Hartley guinea pigs (GP) by having them rebreathe the air entrapped in a closed circuit from which the CO2 was continuously absorbed. Following this slow-developing hypoxemia, a sequence of events concerning the ear could be observed. Firstly, a fluctuation in cochlear action potentials (CAP) was noted. This appeared only at stimulus intensities near the threshold and was not evident at higher intensities. At a mean arterial pO2 level of 30 mm Hg, this phenomenon was observed in 60% of the GP. At a mean pO2 of 24.66 mm Hg, a shift in threshold occurred in all GP. Finally, when the blood pO2 reached an average of 14.92 mm Hg, no CAP response could be elicited, even at click intensity of 120 dB SPL. The 30 mm Hg oxygen concentration in the arterial blood was considered as a "critical level" at which the cochlear function starts to deteriorate in guinea pigs.
D000818:Animals; D003051:Cochlea / Q000502:physiology; D005072:Evoked Potentials, Auditory; D006168:Guinea Pigs; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption
D010100:Oxygen