We studied the effects of vagotomy on gallbladder (GB) motility in prairie dogs and humans with infusion cholescintigraphy. Twelve male prairie dogs were anesthetized and given an intravenous infusion of 120 microCi of diethyl-HIDA for 150 minutes. Images were acquired every 10 minutes. Then cholecystokinin (CCK)-8, 1.5 micrograms/kg, was given as a bolus, and images were acquired for another 30 minutes. We repeated the studies giving 300 micrograms/kg of atropine 20 minutes before administration of CCK-8. All animals underwent truncal vagotomy, and the studies were repeated 1 and 3 months later. The GB filled in a stepwise fashion; partitioning of bile varied from one 10-minute period to the next and averaged 20% +/- 2%/80% +/- 3% during the 150-minute period. Episodic partial GB emptying (ejection fraction 19% +/- 2%; intervals of 70 +/- 5 minutes) occurred during this phase. GB filling and partitioning of bile were unchanged after vagotomy. GB ejection fraction in response to CCK-8 was 69% +/- 6% in controls, 74% +/- 5% after atropine, 78% +/- 8% 4 weeks after vagotomy, and 66% +/- 6% 3 months after vagotomy. Sixteen human subjects were studied after parietal cell vagotomy (six patients) or truncal vagotomy and drainage (10 patients). GB filling average 2.5% +/- 2% per minute in patients who underwent truncal vagotomy and 3% +/- 1% per minute in patients who underwent parietal cell vagotomy. GB emptying in response to CCK-33 (0.02 U/kg/min) was 74% +/- 7% in patients who underwent truncal vagotomy and 82% +/- 4% in patients who underwent parietal cell vagotomy. Thus neither GB filling nor GB emptying in response to CCK was altered by cholinergic blockade or vagotomy.