G. buchananii extract contains bioactive components that act as GABA receptor ligands. A-B: Summary data showing that GABA (50 μM, A, triangle), the GABAB receptor antagonist, phaclofen (PCF, 40 μM; B, star), and the GABAA receptor antagonist picrotoxin (PTX, 30 μM; B, square), did not alter the effects of G. buchananii extract (2 g bark powder/100 ml Krebs, delivered by bath application) on propulsive motility after 5-10 minutes. Recovery of propulsive motility by post-treatment washout was similar to vehicle results for GABA treatment (increasing propulsive motility by up to 70% above baseline at 15-20 minute washout intervals; (A, bracket with asterisk; P<0.05). A slower recovery was observed during washout after treatment using the extract in combination with picrotoxin (PTX, 30 μM) or phaclofen (PCF, 40 μM). In these cases, motility was still significantly lower than that of vehicle after 20 minutes of washout (bracket with asterisk in B; P<0.05).