Effects of sulfobromophthalein excretion on biliary lipid secretion in humans and dogs

The effect of sulfobromophthalein (BSP) on biliary lipid secretion was investigated in 12 cholecystectomized subjects, using a duodenal marker-perfusion technique. A 1-h basal period was followed by intravenous BSP infusion over 3 h, achieving the maximal excretory rate (Tm). The calculated Tm was not different from the measured maximal output. At BSP Tm, bile salt secretion was unchanged, but phospholipid, cholesterol, and bilirubin secretion were markedly reduced. Biliary lipid composition changed accordingly, higher molar percent bile salts but lower phospholipid and cholesterol. In six cholecystectomized dogs with chronic duodenal fistulas, bile was collected directly from the common duct while bile salt secretion was maintained by intravenous taurocholic acid infusion. After a 2-h control period, sufficient BSP was added to create either maximal (Tm) or submaximal conditions. BSP did not alter bile salt secretion but caused a dose-related decrease in phospholipid and cholesterol secretion. Bilirubin excretion was also reduced, whereas bile flow increased. Thus, BSP is hydrocholeretic but decreases phospholipid, cholesterol, and bilirubin secretion in both humans and dogs. The effect on biliary lipid composition is probably through a physical interaction with biliary micelles.