The role of aquaporin water channels in fluid secretion by the exocrine pancreas

B. Burghardt, S. Nielsen, M. C. Steward

Research output: Article

24 Citations (Scopus)

Abstract

The mammalian exocrine pancreas secretes a near-isosmotic fluid over a wide osmolarity range. The role of aquaporin (AQP) water channels in this process is now becoming clearer. AQP8 water channels, which were initially cloned from rat pancreas, are expressed at the apical membrane of pancreatic acinar cells and contribute to their osmotic permeability. However, the acinar cells secrete relatively little fluid and there is no obvious defect in pancreatic function in AQP8 knockout mice. Most of the fluid secreted by the pancreas is generated by ductal epithelial cells, which comprise only a small fraction of the gland mass. In the human pancreas, secretion occurs mainly in the intercalated ducts, where the epithelial cells express abundant AQP1 and AQP5 at the apical membrane and AQP1 alone at the basolateral membrane. In the rat and mouse, fluid secretion occurs mainly in the interlobular ducts where AQP1 and AQP5 are again co-localized at the apical membrane but appear to be expressed at relatively low levels. Nonetheless, the transepithelial osmotic permeability of rat interlobular ducts is sufficient to support near-isosmotic fluid secretion at observed rates. Furthermore, apical, but not basolateral, application of Hg 2+ significantly reduces the transepithelial osmotic permeability, suggesting that apical AQP1 and AQP5 may contribute significantly to fluid secretion. The apparently normal fluid output of the pancreas in AQP1 knockout mice may reflect the presence of AQP5 at the apical membrane.

Original languageEnglish
Pages (from-to)143-153
Number of pages11
JournalThe Journal of Membrane Biology
Volume210
Issue number2
DOIs
Publication statusPublished - márc. 2006

Fingerprint

Fluids and Secretions
Exocrine Pancreas
Aquaporins
Pancreas
Membranes
Permeability
Acinar Cells
Knockout Mice
Epithelial Cells
Osmolar Concentration

ASJC Scopus subject areas

  • Biophysics
  • Physiology
  • Cell Biology

Cite this

The role of aquaporin water channels in fluid secretion by the exocrine pancreas. / Burghardt, B.; Nielsen, S.; Steward, M. C.

In: The Journal of Membrane Biology, Vol. 210, No. 2, 03.2006, p. 143-153.

Research output: Article

@article{c48a01216eb3469fb632b75742a41de8,
title = "The role of aquaporin water channels in fluid secretion by the exocrine pancreas",
abstract = "The mammalian exocrine pancreas secretes a near-isosmotic fluid over a wide osmolarity range. The role of aquaporin (AQP) water channels in this process is now becoming clearer. AQP8 water channels, which were initially cloned from rat pancreas, are expressed at the apical membrane of pancreatic acinar cells and contribute to their osmotic permeability. However, the acinar cells secrete relatively little fluid and there is no obvious defect in pancreatic function in AQP8 knockout mice. Most of the fluid secreted by the pancreas is generated by ductal epithelial cells, which comprise only a small fraction of the gland mass. In the human pancreas, secretion occurs mainly in the intercalated ducts, where the epithelial cells express abundant AQP1 and AQP5 at the apical membrane and AQP1 alone at the basolateral membrane. In the rat and mouse, fluid secretion occurs mainly in the interlobular ducts where AQP1 and AQP5 are again co-localized at the apical membrane but appear to be expressed at relatively low levels. Nonetheless, the transepithelial osmotic permeability of rat interlobular ducts is sufficient to support near-isosmotic fluid secretion at observed rates. Furthermore, apical, but not basolateral, application of Hg 2+ significantly reduces the transepithelial osmotic permeability, suggesting that apical AQP1 and AQP5 may contribute significantly to fluid secretion. The apparently normal fluid output of the pancreas in AQP1 knockout mice may reflect the presence of AQP5 at the apical membrane.",
keywords = "Aquaporins, Epithelial transport, Exocrine secretion, Isosmotic fluid transport, Osmotic permeability, Paracellular pathway, Water channels",
author = "B. Burghardt and S. Nielsen and Steward, {M. C.}",
year = "2006",
month = "3",
doi = "10.1007/s00232-005-0852-6",
language = "English",
volume = "210",
pages = "143--153",
journal = "Journal of Membrane Biology",
issn = "0022-2631",
publisher = "Springer New York",
number = "2",

}

TY - JOUR

T1 - The role of aquaporin water channels in fluid secretion by the exocrine pancreas

AU - Burghardt, B.

AU - Nielsen, S.

AU - Steward, M. C.

PY - 2006/3

Y1 - 2006/3

N2 - The mammalian exocrine pancreas secretes a near-isosmotic fluid over a wide osmolarity range. The role of aquaporin (AQP) water channels in this process is now becoming clearer. AQP8 water channels, which were initially cloned from rat pancreas, are expressed at the apical membrane of pancreatic acinar cells and contribute to their osmotic permeability. However, the acinar cells secrete relatively little fluid and there is no obvious defect in pancreatic function in AQP8 knockout mice. Most of the fluid secreted by the pancreas is generated by ductal epithelial cells, which comprise only a small fraction of the gland mass. In the human pancreas, secretion occurs mainly in the intercalated ducts, where the epithelial cells express abundant AQP1 and AQP5 at the apical membrane and AQP1 alone at the basolateral membrane. In the rat and mouse, fluid secretion occurs mainly in the interlobular ducts where AQP1 and AQP5 are again co-localized at the apical membrane but appear to be expressed at relatively low levels. Nonetheless, the transepithelial osmotic permeability of rat interlobular ducts is sufficient to support near-isosmotic fluid secretion at observed rates. Furthermore, apical, but not basolateral, application of Hg 2+ significantly reduces the transepithelial osmotic permeability, suggesting that apical AQP1 and AQP5 may contribute significantly to fluid secretion. The apparently normal fluid output of the pancreas in AQP1 knockout mice may reflect the presence of AQP5 at the apical membrane.

AB - The mammalian exocrine pancreas secretes a near-isosmotic fluid over a wide osmolarity range. The role of aquaporin (AQP) water channels in this process is now becoming clearer. AQP8 water channels, which were initially cloned from rat pancreas, are expressed at the apical membrane of pancreatic acinar cells and contribute to their osmotic permeability. However, the acinar cells secrete relatively little fluid and there is no obvious defect in pancreatic function in AQP8 knockout mice. Most of the fluid secreted by the pancreas is generated by ductal epithelial cells, which comprise only a small fraction of the gland mass. In the human pancreas, secretion occurs mainly in the intercalated ducts, where the epithelial cells express abundant AQP1 and AQP5 at the apical membrane and AQP1 alone at the basolateral membrane. In the rat and mouse, fluid secretion occurs mainly in the interlobular ducts where AQP1 and AQP5 are again co-localized at the apical membrane but appear to be expressed at relatively low levels. Nonetheless, the transepithelial osmotic permeability of rat interlobular ducts is sufficient to support near-isosmotic fluid secretion at observed rates. Furthermore, apical, but not basolateral, application of Hg 2+ significantly reduces the transepithelial osmotic permeability, suggesting that apical AQP1 and AQP5 may contribute significantly to fluid secretion. The apparently normal fluid output of the pancreas in AQP1 knockout mice may reflect the presence of AQP5 at the apical membrane.

KW - Aquaporins

KW - Epithelial transport

KW - Exocrine secretion

KW - Isosmotic fluid transport

KW - Osmotic permeability

KW - Paracellular pathway

KW - Water channels

UR - http://www.scopus.com/inward/record.url?scp=33748371635&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33748371635&partnerID=8YFLogxK

U2 - 10.1007/s00232-005-0852-6

DO - 10.1007/s00232-005-0852-6

M3 - Article

C2 - 16868672

AN - SCOPUS:33748371635

VL - 210

SP - 143

EP - 153

JO - Journal of Membrane Biology

JF - Journal of Membrane Biology

SN - 0022-2631

IS - 2

ER -