Effects of potassium ions on the impulse activity of the ampullae of Lorenzini of the skate.

Perfusion of the basal membrane of the ampullae of Lorenzini with high potassium solution caused a substantial increase in the resting firing rate. This effect was not accompanied by any change in the threshold of the afferent fibres. The low potassium solution caused a decrease in the resting firing rate. When synaptic transmission was abolished by high Mg2+ solution, succeeding perfusion with 10 mM K+ did not induce responses in the afferent fibres. The role of potassium ions in the activity of the ampullae of Lorenzini is discussed.