Referenced in: none

Automatically associated channels: Kir2.3

Title: Kynurenic acid distinguishes kainate and quisqualate receptors in the vertebrate retina.

Authors: P A Coleman, S C Massey, R F Miller

Journal, date & volume: Brain Res., 1986 Aug 27 , 381, 172-5

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/3019473

Abstract
Excitatory amino acid receptors (EAARs) underlie major synaptic pathways in the brain, retina and spinal cord. Several subclasses of EAARs have been proposed, based on pharmacological studies using a variety of agonists and antagonists. Kynurenic acid (Kyn), a metabolite of tryptophan, has been recently proposed as a potent EAAR antagonist. In this report, we show that Kyn can be used to separate two distinct classes of EAAR in the vertebrate retina: it blocks kainic acid (KA) responses but has minimal effects on responses mediated by quisqualate (QQ). At concentrations which block the KA responses, Kyn also blocks the light-evoked synaptic responses of all types of third-order neurons in the retina. These results suggest that KA receptors are the major receptor subtypes which underlie synaptic transmission and that QQ receptors are minimally utilized by light-activated pathways under the conditions of our experiments.