The posterior semicircular canal of the frog was isolated in Ringers' solution. An apparatus for constant aspiration was devised which was attached to the end of the posterior canal isolated to make the ampullofugal deviation of the cupula in the posterior canal, and the action potential in the ampullar branch of the vestibular nerve was led off by a micro-suction electrode. From the ampullar branch of the vestibular nerve almost identical responses were recorded by an electronic counter: about 1000 spikes above 50V for 7 seconds.
Next, the influence of aminoglycosides on the ampullar receptors of the isolated posterior semicircular canal was studied. Gentamycin and Panimycin inhibited the response to the stimulation of ampullar receptor at 140r/ml, and reduced the electrical activity to 50% at 210/ml.
Sagamicin inhibited the response at 210/ml and reduced the activity to 40% at 350/ml.