Regulation of Hepatic Biliary Secretion

Abstract

Bile formation is a complex process comprised of four separate physiologic mechanisms operating at two anatomical sites (29, 129, 131). The initial event occurs in the hepatocyte or at the bile canaliculus, and at least two processes are responsible for total canalicular secretion: the active transport of bile acids into the canalicular lumen, and the production of the bile salt-independent canalicular fraction (BSICF), which is unrelated to bile salt secretion at the canaliculus and which may involve the active transport of sodium (25, 26). As canalicular bile moves into the biliary ducts the secretion may be further modified by the addition of water and electrolytes from the biliary ductular epithelium or, in some cases, by absorption of water and electrolytes. During digestion, bile secretion increases considerably. Many of the fac­ tors involved in this regulation are not known. This review deals primarily with the neurohumoral factors thought likely to be important regulators of bile water and electrolyte secretion. Although a brief description of current understanding of the mechanisms of bile formation is necessary, the subject has been reviewed extensively recently (23, 24, 33, 55, 130).