Evidence for a neurotransmitter role of glutamate in guinea pig myenteric plexus neurons.
Longitudinal muscle-myenteric plexus strips of the guinea pig ileum were used to investigate a possible transmitter role of glutamate (Glu) in the enteric nervous system. Glu was released from this nerve muscle preparation by high K(+)-depolarization in a Ca2(+)-dependent manner, by electrical field stimulation and by the ganglionic stimulant dimethylphenylpiperazinium which indicates its neural origin. Contractions of the longitudinal muscle evoked by electrical stimulation of the myenteric nerves or by Glu, were significantly reduced by the N-methyl-D-aspartate (NMDA)-receptor antagonist FR115427 (9 and 18 microM), whereas contractions induced by histamine were unaffected. The results show that the amino acid Glu is likely to play an excitatory neurotransmitter role via NMDA receptors in the myenteric plexus of the guinea pig.
Sinský
M
M
Institute of Experimental and Clinical Pharmacology, University of Graz, Austria.
Donnerer
J
J
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004246:Dimethylphenylpiperazinium Iodide / Q000494:pharmacology; D004558:Electric Stimulation; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005260:Female; D005731:Ganglionic Stimulants / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism*; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D007082:Ileum / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D066298:In Vitro Techniques; D007546:Isoquinolines / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D009197:Myenteric Plexus / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D012970:Sodium Glutamate / Q000494:pharmacology; D044005:Tetrahydroisoquinolines; D013779:Tetrodotoxin / Q000494:pharmacology
D018691:Excitatory Amino Acid Antagonists; D005731:Ganglionic Stimulants; D007546:Isoquinolines; D018377:Neurotransmitter Agents; D044005:Tetrahydroisoquinolines; C084456:1-methyl-1-phenyl-1,2,3,4-tetrahydroisoquinoline; D018698:Glutamic Acid; D013779:Tetrodotoxin; D004246:Dimethylphenylpiperazinium Iodide; D006632:Histamine; D011188:Potassium; D012970:Sodium Glutamate