Hormonal contributions to biliary secretion.

Gastrointestinal hormones appear to be important modulators of bile flow and composition. Insulin and glucagon induce choleresis at physiologic levels and may alter lipid output and concentration as well. The effects of many hormones such as insulin, glucagon, secretin, and pancreatic polypeptide are at least partially independent of their effects on neurovascular factors. Furthermore, recently studied hormones such as somatostatin, vasoactive intestinal polypeptide, and pancreatic polypeptide have also been shown not only to alter bile flow but to affect bile composition. Understanding the role of gastrointestinal hormones in hepatic physiology may elucidate the causes of gallstone formation, disorders of biliary excretion, and hypercholesteremic states.