Gastric surgery induces an increased incidence of gallstones. To investigate the changes in gallbladder kinetics after gastric resection, 20 male patients were studied: ten patients undergoing cholecystectomy for gallstones developed after Billroth II gastric resection and ten patients undergoing cholecystectomy for cholelithiasis without previous abdominal surgery. Longitudinal strips from the gallbladder wall were suspended in an organ bath and the isometric tension recorded. Dose-response curves to cholecystokinin-octapeptide and carbachol were obtained. Half the maximal response to cholecysto-kinin-octapeptide was 0.50 +/- 0.11 x 10(-7) M in the first group and 1.36 +/- 0.37 x 10(-7) M in the second group (P < 0.05). The ED50 to carbachol was 24.33 +/- 2.69 x 10(-7) M in the gastrectomy group and 40.39 +/- 5.01 x 10(-7) M in the control group (P < 0.01). There was no significant difference in the maximal contractile response either to cholecystokinin-octa-peptide or carbachol in the two groups. Our study shows an increased gallbladder sensitivity to cholecystokinin-octapeptide and carbachol in patients with gallstones developed after Billroth II gastric resection.