Calcium-dependent release of endogenous glutamate from vascularly perfused rat stomach in vitro.
To investigate a possible physiological role for glutamate in the stomach, release of endogenous glutamate from an isolated vascularly-perfused rat stomach preparation was studied. Glutamate was measured by the bioluminescence assay method. High concentrations of KCI (30-75 mM) induced a dose-dependent release of glutamate. This KCI-induced release of glutamate was abolished in calcium-free medium containing ethylene glycol bis (beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA). Electrical stimulation of the vagus nerves also induced a release of glutamate. This vagal stimulation-induced release of glutamate was abolished by both calcium removal and tetrodotoxin (TTX). Amounts of 13 other amino acids in the medium, detectable by the automatic amino-acid analyzer, were not significantly affected by both high-K+ and the vagal stimulation. These results provide additional evidence that glutamate probably serves as a neurotransmitter in the stomach.
Okuma
Y
Y
Department of Pharmacology, Kochi Medical School, Japan.
Yokotani
K
K
Nakamura
K
K
Osumi
Y
Y
D000818:Animals; D002118:Calcium / Q000502:physiology*; D004558:Electric Stimulation; D005753:Gastric Mucosa / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013270:Stomach / Q000187:drug effects*; D013997:Time Factors; D014630:Vagus Nerve / Q000187:drug effects
D018698:Glutamic Acid; D002118:Calcium