Molecular Mechanism of Pancreatic Bicarbonate Secretion.
- Author:
Min Goo LEE
1
;
Je Woo KIM
;
Kyung Hwan KIM
;
Shmuel MUALLEM
Author Information
1. Department of Pharmacology and Brain Korea 21 Project for Medical Sciences, Yonsei University College of Medicine, Seoul, Korea. SHMUEL.MUALLEM@UTSouthwestern. edu
- Publication Type:Review
- Keywords:
Pancreas;
Bicarbonate;
CFTR;
Transporter
- MeSH:
Absorption;
Cystic Fibrosis Transmembrane Conductance Regulator;
Diffusion;
Epithelial Cells;
Membranes;
Pancreas;
Pancreatic Ducts;
Phenobarbital
- From:The Korean Journal of Physiology and Pharmacology
2002;6(3):131-138
- CountryRepublic of Korea
- Language:English
-
Abstract:
Thanks to recent progress in availability of molecular and functional techniques it became possible to search for the basic molecular and cellular processes that mediate and control HCO3- and fluid secretion by the pancreatic duct. The coordinated action of various transporters on the luminal and basolateral membranes of polarized epithelial cells mediates the transepithelial HCO3- transport, which involves HCO3- absorption in the resting state and HCO3- secretion in the stimulated state. The overall process of HCO3- secretion can be divided into two steps. First, HCO3- in the blood enters the ductal epithelial cells across the basolateral membrane either by simple diffusion in the forms of CO2 and H2O or by the action of an Na+-coupled transporter, a Na+-HCO3- cotranporter (NBC) identified as pNBC1. Subsequently, the cells secrete HCO3- to the luminal space using at least two HCO3- exit mechanisms at the luminal membrane. One of the critical transporters needed for all forms of HCO3- secretion across the luminal membrane is the cystic fibrosis transmembrane conductance regulator (CFTR). In the resting state the pancreatic duct, and probably other HCO3- secretory epithelia, absorb HCO3-. Interestingly, CFTR also control this mechanism. In this review, we discuss recent progress in understanding epithelial HCO3- transport, in particular the nature of the luminal transporters and their regulation by CFTR.
