The effect of GABA antagonism on propulsive activity of the guinea-pig large intestine.

Possible involvement of gamma-aminobutyric acid (GABA) in intestinal motility of the guinea-pig has been investigated using the speed of propulsion of faecal pellets along isolated segments of guinea-pig distal colon, and the rate of pellet expulsion from freshly excised colon. GABA antagonism, by bicuculline or by tachyphylaxis to GABA, substantially reduced intestinal motility and generally reduced the amplitude of the reflex contraction associated with pellet propulsion. These results support the view that GABAergic mechanisms may be involved in the propulsive activity of the guinea-pig distal colon.