Using an in vivo microscopy technique, we studied the microcirculatory changes in sodium taurocholate-induced pancreatitis in rats. With a computerized image analyzer system, blood flow, vascular permeability changes, and capillary densities were measured. Intraductal infusion of 0.4 ml saline had only minor effects on the microcirculation. Various concentrations and volumes of sodium taurocholate solutions were infused into the pancreatic duct. Sodium taurocholate (0.4 ml, 4%) led to increased vascular permeability preceding stasis within 232 +/- 47 s, followed by hemorrhagic necrosis in the head of the pancreas. In the corpus close to the tail of the pancreas capillary blood flow was maintained. In conclusion, this study shows that the microcirculation of the pancreas can be excellently investigated with in vivo microscopy. With this method, tremendous distribution disturbances of the microcirculation in the pancreas can be seen in the course of acute pancreatitis. Vascular permeability changes and stasis of the microcirculation represent the primary microcirculatory events in acute pancreatitis induced by sodium taurocholate in the areas where hemorrhagic necrosis occurs.