It has been reported that ethacrynic acid (ETA) reduces the ampullar and saccular endolymphatic potentials (EP), whereas furosemide inhibits only saccular EP and has no effect on ampullar EP. In 1979, one of the present authors (J. Kusakari) reported that the nystagmus produced by stimulation of the peripheral organ was greatly inhibited by ETA. In the present study we examined the effect of EP depression on the otolith organ.
Normal and unilateral labyrinthectomized albino guinea pigs were fixed on a tilt table and counter-rolling (CR) of the eyes was measured by the photographic method. ETA (50, 100, 150 mg/kg) and furosemide (100 mg/kg) were injected intravenously, and measurements were recorded for 30-150 minutes. Although 50 mg/kg ETA and 100 mg/kg furosemide had no significant effect, 100 and 150 mg/kg ETA significantly reduced the CR of the eyes, and the time course of reduction in CR was quite similar to that in AEP.
It is concluded that the function of the utricle is inhibited by the reduction of the endolymphatic potential.