title: Effect of sulphur containing amino acids on [3H]-acetylcholine release from amacrine cells of the rabbit retina.
abstract: 1. The effects of the sulphur containing amino acids, homocysteic acid, homocysteine sulphinic acid, cysteic acid and cysteine sulphinic acid on the release of [3H]-acetylcholine ([3H]-ACh) from the cholinergic amacrine cells of the rabbit retina were examined. 2. All the compounds stimulated the spontaneous resting release and abolished the light-evoked release of [3H]-ACh. Except for homocysteine sulphinic acid these actions occurred at concentrations that did not affect the erg b-wave amplitude, indicating a site of action at the inner retina. 3. N-methyl-D-aspartate (in Mg(2+)-containing medium) clearly blocked the effects of homocysteic acid and homocysteine sulphinic acid on the resting release of [3H]-ACh but had no effect on the actions of cysteic acid and cysteine sulphinic acid. 4. Since N-methyl-D-aspartate is an antagonist of the light-evoked endogenous bipolar cell transmitter released onto cholinergic cells, these results are consistent with the suggestion that homocysteic acid or homocysteine sulphinic acid may be a transmitter released from this subpopulation of bipolar cells. 5. The present experiments indicate the existence of excitatory amino acids that have closer pharmacological properties to a bipolar cell transmitter than glutamate but it remains to be seen whether homocysteic acid or homocysteine sulphinic acid occur in these particular bipolar cells.
authors.affiliation: Department of Pharmacology (UMDS), St Thomas's Hospital, London.
authors.forename: M J
authors.initials: MJ
authors.lastname: Neal
authors.forename: J R
authors.initials: JR
authors.lastname: Cunningham
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000603:Amino Acids, Sulfur / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000818:Animals; D003544:Cysteic Acid / Q000494:pharmacology; D004596:Electroretinography; D006710:Homocysteine / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D016202:N-Methylaspartate / Q000494:pharmacology; D010775:Photic Stimulation; D011817:Rabbits; D012160:Retina / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000603:Amino Acids, Sulfur; D006710:Homocysteine; C007956:homocysteic acid; C010982:homocysteinesulfinic acid; D016202:N-Methylaspartate; D003544:Cysteic Acid; D000109:Acetylcholine