Amino acid receptors mediate calcium permeability in synaptosomes from rat brain
Selected acidic amino acids and amino acid analogues were shown to increase the Ca/sup 2 +/ permeability of the plasma membrane of synaptosomes isolated from rat brain. Increased synaptosomal Ca/sup 2 +/ content was measured by uptake of /sup 45/Ca/sup 2 +/. Increased intrasynaptosomal free calcium was measured by the fluorescent calcium indicators indo 1 and quin 2. The increase in calcium permeability was maximal within 0.5 seconds (the limit of resolution of the methods used). The calcium permeability system(s) being modulated by the receptors appears to be Ca/sup 2 +/ channels but has properties different from the voltage dependent Ca/sup 2 +/ channels. Four different types of receptors have been observed; a kainate receptor antagonized by quisqualate, an L-cysteine sulfinate receptor, a 2-amino-2-phosphono-valerate receptor and an N-methyl-D-aspartate receptor. Each type of receptor is highly specific in ligand binding and none were activated or antagonized by aspartate or glutamate at concentrations up to 10 mM. Currently available data indicate substantial differences in ligand specificity between these presynaptic receptors and the postsynaptic receptors which have been classified by electrophysiological and radio-ligand binding studies. The neurotoxicity of kainate, L-cysteine sulfinate and N-methyl-D-aspartate may be due in part to metabolic and electrophysiological disturbances resulting from increased calcium in neurons having these receptors.
- Research Organization:
- Univ. of Pennsylvania Medical School, Philadelphia
- OSTI ID:
- 5019728
- Report Number(s):
- CONF-8606151-
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:6; Conference: 76. annual meeting of the Federation of American Society for Experimental Biology, Washington, DC, USA, 8 Jun 1986
- Country of Publication:
- United States
- Language:
- English
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AMINO ACIDS
RECEPTORS
CALCIUM COMPOUNDS
MEMBRANE TRANSPORT
CELL MEMBRANES
PERMEABILITY
BIOCHEMICAL REACTION KINETICS
BRAIN
CALCIUM 45
FLUORESCENCE
LIGANDS
NERVES
RATS
TRACER TECHNIQUES
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METAL COMPOUNDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CALCIUM ISOTOPES
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CENTRAL NERVOUS SYSTEM
DAYS LIVING RADIOISOTOPES
EVEN-ODD NUCLEI
INTERMEDIATE MASS NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LUMINESCENCE
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
NERVOUS SYSTEM
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RODENTS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques