Yeungnam Univ J Med.  1991 Dec;8(2):95-105. 10.12701/yujm.1991.8.2.95.

Effect of GABA on the contratility of small intestine isolated from rat

• Huh JY
• Kwon OC
• Ha JH
• Lee KY
• Kim WJ

• KMID: 2377364
• DOI: http://doi.org/10.12701/yujm.1991.8.2.95

Abstract

This study was designed to investigate the effect of GABA and related substances on the spontaneous contraction of rat small intestine. The rats (Sprague-Dawley), weighing 200-250g, were sacrificed by cervical dislocation, and the small intestine was isolated. Longitudinal muscle strips from duodenum, jejunum and ileum were suspended in Biancani's isolated muscle chambers and myographied isometrically. GABA and muscimol, a GABA A receptor agonist relaxed the duodenum and jejunum significantly, but baclofen-induced relaxation in those muscle strips negligible. The effectiveness of GABA and muscimol in various regions were the greatest on duodenum, and greater on jejunum than on ileum The effect of GABA and muscimol was antagonized by bicuculline, a competitive GABA A receptor antagonist and picrotoxin, a noncompetitive GABA A receptor antagonist. Duodenal relaxation induced by GABA and muscimol was unaffected by hexamethonium, but was prevented by tetrodotoxin. These results suggest that GABA inhibit the contractility of smooth muscle with distinct regional difference of efficacy, and the site of inhibitory action is the GABA A receptor existing at the presynaptic membrane of postganglionic excitatory nerves.

Keyword

GABA; Small intestine; Presynaptic; Regional difference

MeSH Terms

Animals
Bicuculline
Dislocations
Duodenum
GABA-A Receptor Agonists
GABA-A Receptor Antagonists
gamma-Aminobutyric Acid*
Hexamethonium
Ileum
Intestine, Small*
Jejunum
Membranes
Muscimol
Muscle, Smooth
Picrotoxin
Rats*
Receptors, GABA-A
Relaxation
Tetrodotoxin
Bicuculline
GABA-A Receptor Agonists
GABA-A Receptor Antagonists
Hexamethonium
Muscimol
Picrotoxin
Receptors, GABA-A
Tetrodotoxin
gamma-Aminobutyric Acid