INHIBITORY EFFECTS OF ADENOSINE 5＇-TRIPHOSPHATE ON COCHLEAR FUNCTION OF GUINEA PIG

Objective To study effects of adenosine 5‘-triphosphate (ATP) on cochlear function of guinea pig. Methods After perfusion of ATP into perilymphatic spaces of the guinea pig cochlea, summating potential (SP) , cochlear microphonic (CM) , auditory nerve compound action potential (CAP) , distortion product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) were measured. Results The results showed concentration-dependent effect of ATP on the response alterations of bioelectric activity in cochlea. Administration of lmmol/L ATP caused an increase both in the amplitude of the SP and in the threshold of ABR, a decrease in amplitude of the CAP and DPOAE. In addition, response alterations of the CAP and DPOAE showed in an intensity-and frequency-dependent manner, respectively. At levels of 20-70dB nHL sound intensity, lmmol/L ATP caused a significant decrease in the CAP amplitude, while at moderate and high frequency ranges of 2-8kHz it reduced DPOAE amplitude significantly. 330μmol/L ATP also increased the threshold of ABR. Conclusion ATP through perilymphatic perfusion could inhibit cochlear function of guinea pig.