Premium
Cl‐Dependent Na‐H Exchange: A Novel Colonic Crypt Transport Mechanism
Author(s) -
BINDER HENRY J.,
RAJENDRAN VAZHAIKKURICHI M.,
GEIBEL JOHN P.
Publication year - 2000
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.2000.tb05222.x
Subject(s) - crypt , chemistry , bicarbonate , apical membrane , intracellular ph , epithelial polarity , ion transporter , secretion , sodium–hydrogen antiporter , intracellular , membrane , biophysics , biochemistry , sodium , endocrinology , biology , organic chemistry
A bstract : This communication summaries a series of observations of the transport function of the crypt of the rat distal colon. Development of methods to study both 22 Na uptake by apical membrane vesicles prepared from crypt cells and intracellular pH i (pH i ), fluid movement (Jv), and bicarbonate secretion during microperfusion of the crypt has led to the identification of (1) a novel Cl‐dependent Na‐H exchange (Cl‐NHE) that most likely represents the coupling of a Cl channel to a Na‐H exchange isoform that has not as yet been identified and (2) bicarbonate secretion that appears to be most consistent with HCO 3 uptake across the basolateral membrane by a mechanism that is closely linked to Cl transport and its movement across the apical membrane via an anion channel. Na‐dependent fluid absorption is the constitutive transport process in the crypt, while fluid secretion is regulated by one or more neurohumoral agonists. Cl‐NHE is responsible for both the recovery/regulation of pHi in crypt cells to an acid load and fluid absorption.