[The ampullar endolymhatic potential in the guinea pigs].

The purpose of this paper is to understand the physiologic feature of the ampullar endolymphatic potential (AEP) in the guinea pigs (n = 35). The high input impedence microelectrode amplifier was used. The effects of asphyxia, furosemide and ischemia on the AEP were observed. The AEP was 4.55 +/- 1.35 mV, (n = 35) in normal. The potential decreased to 2.8 +/- 0.8 mV from the original level in two minutes of asphyxia. When the respirator was turned on the AEP started to rise abruptly after a latency. In all instances there was an overshoot above the preasphyxia level. When furosemide was administered i.v. at 100 mg/kg, no effects were seen in the AEP. After obstruction of the ascending aorta to cause ischemia, the AEP continued to decline until it reached a minimum of -19.4 +/- 1.7 mV in 52.5 +/- 9.6 minutes and slowly returned to zero line in about 150 minutes. There was no obovious effect after furosemide injection. The results suggest that AEP may deffer from as the positive potential in cochlea. It is produced in the specialized cells (dark cells) of the ampullar and has special electro-physiologic characteristics.