Effects of kainic acid on synaptic transmission in electroreceptors (the ampullae of Lorenzini) of skates.

1. Effects of kainic acid (KA) on resting and evoked activities of the ampullary electroreceptor were studied in marine skates (Raja clavata). 2. Perfusion of the basal membrane with 10(-6)-10(-9) M KA produced significant and reversible changes in impulse activity depending on initial firing rate. 3. When synaptic transmission was blocked by perfusion with elevated Mg2+, the resting and evoked activities were restored if KA was added. 4. The results are consistent with the view that KA is a potent excitant of the ampullae receptors and its effects appear to be presynaptic.