Characterization of transmitter release as a response of vertebrate neural tissue to erythrosin B.
A rat cerebral cortical slice preparation was used to study the response of transmitter release to the application of the food dye, Erythrosin B, a tetraiodinated derivative of fluorescein. Erythrosin B (100 microM) stimulated net release of previously taken up [3H]norepinephrine and [3H]gamma-aminobutyric acid (GABA). The Erythrosin-induced release of GABA (the only transmitter studied) occurred in the absence of added Ca2+, and in the presence of tetrodotoxin (TTX). Ultrastructural analysis of the vesicle content of frog neuromuscular junctions treated with Erythrosin B revealed a diminution in the number of synaptic vesicles present in the nerve terminal. By using fluorescein and some halogen-substituted derivatives including Erythrosin B, it was found that incubation with the unhalogenated compound caused no net release, whereas incubation with the iodine-, chlorine- or bromine-substituted compound did cause release. It was also found that somewhat greater release induced by Erythrosin B (at 100 microM) occurred in the light than in the dark. That Erythrosin B inhibits the Na+,K+,Mg2+-ATPase was confirmed in this preparation; it did so in both light and dark. The discrepancy between release and Na+,K+,Mg2+-ATPase blockade in the dark suggests that release either occurs by some other mechanism than by Na+,K+,Mg2+-ATPase blockade, or that an additional light-dependent process contributes to the release. We conclude that Erythrosin B can presumably induce net release of transmitters generally, that release does not occur via the TTX-sensitive Na+ channel, that release via vesicles does occur, and that light somewhat enhances the release.
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase; D002540:Cerebral Cortex / Q000378:metabolism*; D004923:Erythrosine / Q000494:pharmacology*; D005452:Fluoresceins / Q000494:pharmacology*; D066298:In Vitro Techniques; D008854:Microscopy, Electron; D009469:Neuromuscular Junction / Q000187:drug effects* / Q000648:ultrastructure; D018377:Neurotransmitter Agents / Q000378:metabolism*; D011894:Rana pipiens; D051381:Rats; D011919:Rats, Inbred Strains; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D009435:Synaptic Transmission / Q000187:drug effects*
D005452:Fluoresceins; D018377:Neurotransmitter Agents; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; D000254:Sodium-Potassium-Exchanging ATPase; D004923:Erythrosine