The effect of the cationic composition in perilymph upon the N1 latency of the guinea pig.

Although a suitable cationic composition in perilymph is known to be essential for the generation of N1, the effect of the cationic change upon the N1 latency has never been investigated in detail. The scala tympani was perfused with an artificial perilymph with a high K+, low Na+ or low Ca2+ content, with simultaneous measurement by an ion-selective microelectrode to observe its effect upon the N1 latency. An excess of K+, a depletion of Na+ and a depletion of Ca2+ in perilymph individually suppressed the N1 amplitude and elevated the N1 threshold. The N1 latency was not prolonged in the high K+ group but the significant prolongation was observed in the other two groups.