Inhibitory effect of taurine on 4-aminopyridine-stimulated release of labelled dopamine from striatal synaptosomes.
4-Aminopyridine (4-AP) stimulated the release of [3H]dopamine from striatal synaptosomes in the rat. At a concentration of 200 microM, 4-aminopyridine increased the spontaneous efflux of dopamine by 170%. The effect of 4-aminopyridine was calcium-dependent, being abolished when calcium was omitted from the incubation medium. Taurine, at a concentration of 25 mM, decreased the stimulatory effect of 4-aminopyridine from 170 to 49%, in the presence of 2.5 mM calcium. When the concentration of calcium in the superfusion medium was reduced to 0.1 mM, taurine had a complete inhibitory effect on the release of [3H]dopamine stimulated by 4-aminopyridine. The effect of taurine was dose-dependent. Glycine had no effect on the release of [3H]dopamine stimulated by 4-aminopyridine, either in the presence of absence of calcium, whereas gamma-aminobutyric acid (GABA) showed a slight inhibitory effect in both conditions. The results suggest that taurine antagonizes the release of [3H]dopamine induced by 4-aminopyridine through an effect mediated by calcium.
D015761:4-Aminopyridine; D000631:Aminopyridines / Q000037:antagonists & inhibitors*; D000818:Animals; D002118:Calcium / Q000502:physiology; D003342:Corpus Striatum / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D005998:Glycine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013574:Synaptosomes / Q000378:metabolism; D013654:Taurine / Q000494:pharmacology*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D000631:Aminopyridines; D013654:Taurine; D005680:gamma-Aminobutyric Acid; D015761:4-Aminopyridine; D002118:Calcium; D005998:Glycine; D004298:Dopamine