Immunoreactive insulin in bile and pancreatic juice of rat.

Immunoreactive insulin (IRI) was determined in the bile and pancreatic juice of rats. Recovery studies in which known amounts of insulin were added to samples of these fluids indicated that the IRI values corresponded closely to total recovery. The concentration of IRI in bile and pancreatic juice was greater than the concentration in arterial plasma and less than the concentration in hepatic portal venous plasma adjacent to the liver. Elevation of the circulating IRI concentration in fasting anaesthetized animals by intravenously administered glucose or insulin produced a concomitant increase in the concentration of IRI in bile and pancreatic juice. In fasting conscious animals there was a circadian variation in the concentration of IRI in bile and pancreatic juice similar to the variation of IRI in the circulation. The total amount of IRI in the bile and pancreatic juice of fasting conscious rats during 24 h was in excess of 4 mU/kg body weight. These studies demonstrate that considerable quantities of IRI are transferred from the circulation into the bile and pancreatic juice of rats.