[Effects of asphyxia on endocochlear direct-current potential in guinea pig].
OBJECTIVE
To investigate the mechanism of auditory function disturbance due to asphyxiants.


METHODS
Guinea pigs with nice auricle reflex were selected in the experiment. The changes of endocochlear direct-current potential (EP) were detected when apnea and after artificial respiration, using the stria vascularis method.


RESULTS
(1) The original EP of experimental group was (76.4+/-8.4) mV, and the original EP of control group was (80.8+/-8.4) mV, there was no significant difference between them. (2) During apnea, the EP of all the guinea pigs decreased precipitously after incubation period of 8 to 34 seconds. The decreasing rate of EP was positively correlated to the incubation period (P=0.008). (3) After 3 minutes of apnea, the mean minimum of EP was (-17.5+/-4.4) mV, which was positively correlated with decreasing rate and incubation period (P was 0.0002, 0.000 separately). (4) After artificial respiration, it needed the average time of (85.0+/-16.0) s to return original EP, and 7 cases got an overrun.


CONCLUSIONS
The EP of all the guinea pigs decreased when apnea, which showed the abnormal living circumstance of acoustic hair cells. After 3 minutes of apnea, the EP of all the guinea pigs decreased to negative value, which demonstrated that the functions of acoustic hair cells had not lost within 3 minutes of apnea. After artificial respiration, all the guinea pigs' EP returned to original value, which indicated that the functions of the stria vascularis had not failed irreversibly.
Liu
Xiuli
X
Department of Otolaryngology, the First Affiliated Hospital of China Medical University, Shenyang, 110001, China. yicsun@yahoo.com.cn
Ren
Zhong
Z
Lü
Mei
M
Nakashima
Tsutomu
T
D000818:Animals; D001237:Asphyxia / Q000503:physiopathology*; D003051:Cochlea / Q000503:physiopathology*; D005072:Evoked Potentials, Auditory; D006168:Guinea Pigs; D008564:Membrane Potentials