Figure 3. Colonic motility is significantly faster, in vivo, following administration of luminally acting 5-HT₄R agonists.

Both 5HT4-LA1 (A; N=12) and 5HT4-LA2 (B; 10 mg/kg; N=18) decreased the time to expulsion of a glass bead place 2 cm into the distal colon, as compared to vehicle trials two days earlier, whereas no difference was detected between trials when the vehicle was administered instead of an agonist (C; N=13). D. The agonist, 5HT4-LA1 did not alter the rate of colonic motility when administered in the presence of the 5-HT₄R antagonist, GR113808 (1 mg/kg; N=13). *p≤0.05; **p≤0.01. Data represented as mean ± SEM and analyzed by 2-tailed paired Student t test.