The Effect of High K⁺ Concentration in Perilymph upon the First Order Neuron of the Guinea Pig

Abstract

It is known that the introduction of the high K solution into the perilymphatic space produces the nystagmus initially towards the treated side (irritative nystagmus)lasting for several minutes and towards the opposite side (paralytic nystagmus) thereafter. In order to examine the changes of the vestibular neuron during these period, the single unit action potential was recorded from the superior vestibular nerve of the guinea pig anesthetized with Nembutal and the effect of high K in perilymph upon the interspike interval was examined. Several minutes after the introduction of the saturated K solution in the scala tympani from the middle ear by iontophresis, the interspike interval started to decrease, reached to the about half of the control value in 10 to 15 minutes and suddenly disappeared. It was concluded that the initial irritative nystagmus was induced by the excitation of the primary vestibular nerve and the following paralytic one was due to the abolishment of the nerve activity.