The presence of N-methyl-D-aspartate-type receptors for glutamic acid in the guinea pig myenteric plexus.
The actions of agonists and antagonists of excitatory amino acid receptors were studied in the isolated ileal longitudinal muscle-myenteric plexus preparation of the guinea pig incubated 'in vitro', by recording the contraction of the longitudinal muscle. L-Glutamate, L-aspartate, quinolinate and N-methyl-D-aspartate (NMDA), in concentrations ranging from 10(-6) to 10(-4) M, induced a rapid contraction of this preparation while kainate and quisqualate were not active at a concentration of 10(-4) M. The excitatory amino acid responses were competitively antagonized by 2-amino-5-phosphonovalerate. They were also prevented by Mg2+ ions (0.1-1 mM), by tetrodotoxin 3 X 10(-6) M and by hyoscine 10(-7) M. The last observations suggest that the myenteric cholinergic interneurons are in some way involved in the glutamate-induced ileal contraction. These results demonstrate the existence of receptors for excitatory amino acids (possibly of NMDA type) in the myenteric plexus of the guinea pig.
Moroni
F
F
Luzzi
S
S
Franchi-Micheli
S
S
Zilletti
L
L
D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D005971:Glutamates / Q000494:pharmacology; D018698:Glutamic Acid; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009132:Muscles / Q000187:drug effects / Q000378:metabolism; D009197:Myenteric Plexus / Q000187:drug effects / Q000378:metabolism*; D016202:N-Methylaspartate; D017470:Receptors, Glutamate; D017981:Receptors, Neurotransmitter / Q000145:classification / Q000187:drug effects / Q000378:metabolism*
D005971:Glutamates; D017470:Receptors, Glutamate; D017981:Receptors, Neurotransmitter; D001224:Aspartic Acid; D018698:Glutamic Acid; D016202:N-Methylaspartate