Autoreceptors regulate gamma-[3H]aminobutyric acid release from the guinea pig small intestine.
The possible presence of a presynaptic gamma-aminobutyric acid (GABA) receptor capable of regulating the release of GABA was investigated using the guinea pig small intestine. Muscimol at 10(-8) M and 10(-7) M, but not baclofen at 10(-6) M, inhibited the K+ (40 mM)-evoked Ca2+-dependent release of [3H]GABA from the small intestine preloaded with [3H]GABA, in the presence of 10(-6) M tetrodotoxin. The effect of muscimol on the K+-evoked GABA release was inhibited by bicuculline and furosemide. These results show that the guinea pig small intestine possesses presynaptic GABA receptors which may be involved in the regulation of the evoked GABA release. The presynaptic GABA receptor is bicuculline-sensitive and is probably coupled to the Cl- ion channel.
Taniyama
K
K
Hanada
S
S
Tanaka
C
C
D000818:Animals; D001418:Baclofen / Q000494:pharmacology; D001640:Bicuculline / Q000494:pharmacology; D005260:Female; D005665:Furosemide / Q000494:pharmacology; D006168:Guinea Pigs; D007082:Ileum / Q000502:physiology*; D008297:Male; D009118:Muscimol / Q000494:pharmacology; D009197:Myenteric Plexus / Q000502:physiology; D011188:Potassium / Q000494:pharmacology; D011963:Receptors, GABA-A / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D011963:Receptors, GABA-A; D009118:Muscimol; D013779:Tetrodotoxin; D005680:gamma-Aminobutyric Acid; D005665:Furosemide; D001418:Baclofen; D011188:Potassium; D001640:Bicuculline