effect of intravenous glucagon on the biliary secretion of a cholangiographic agent in man this study was undertaken in an attempt to define the mechanism whereby intravenous glucagon enhanced bile duct and gallbladder opacification at the time of infusion cholangiography seven postoperative gallstone patients with indwelling ttubes were given a 1 h infusion of intravenous iotroxamide at a rate of 41 mgkg body weightmin bile samples were collected by gravity drainage and assayed for iotroxamide and hence biliary iodine concentration at the end of the 1 h infusion the mean biliary excretion rate sem of iotroxamide was 261 34 mgmin and the iodine concentration in bile 97 12 mgml 1 mg of intravenous glucagon given over 30 s at the end of the iotroxamide infusion produced a significant increase in bile flow p less than 001 the excretion rate of iotroxamide rose rapidly following glucagon to reach a peak value of 438 81 mgmin 5 min after the glucagon p less than 005 the enhanced biliary excretion of iotroxamide resulting from the glucagon injection was significant p less than 005 1 3 and 5 but not 10 min after the hormone the intravenous glucagon also caused a small but significant p less than 005 elevation of the biliary iodine concentration to 109 12 mgml 3 min after its injection but by 5 min postglucagon the iodine concentration in bile had reversed to preinjection levels the possible clinical implications of these results are discussed