L-glutamate as possible neurotransmitter in the ampullae of Lorenzini of the skate

Effects of Mg2+, L-glutamate (L-Glu) and L-glutamic acid diethylester (GDEE) on resting and evoked activities of the ampullae of Lorenzini were studied in marine skates (Raja clavata). Perfusion of the basal membrane with 10(-4)-10(-5) M L-Glu produced significant and reversible changes in resting firing rate depending on initial resting rate. When synaptic transmission was blocked by perfusion with elevated Mg2+, the resting activity was restored if L-Glu (10(-4)-10(-5) M) was added. GDEE (10(-3)-10(-4) M) blocked the synaptic transmission. The results are consistent with the view that L-Glu is the synaptic transmitter in the ampullae of Lorenzini of the skate.