Electrogenic H+ Transport and pH Gradients Generated by a V-H+-ATPase in the Isolated Perfused Larval Drosophila Midgut

Electrogenic H+ Transport and pH Gradients Generated by a V-H+-ATPase in the Isolated Perfused... A method for microperfusion of isolated segments of the midgut epithelium of Drosophila larvae has been developed to characterize cellular transport pathways and membrane transporters. Stereological ultrastructural morphometry shows that this epithelium has unusually long tight junctions, with little or no lateral intercellular volume normally found in most epithelia. Amplification of the apical and basal aspects of the cells, by ≈ 17-fold and ≈ 7-fold, respectively, predicts an almost exclusively transcellular transport system for solutes. This correlates with the high lumen-negative transepithelial potential (V t) of 38 to 45 mV and high resistance (R t) of 800 to 1400 Ω • cm2 measured by terminated cable analysis, in contrast to other microperfused epithelia like the renal proximal tubule. Several blockers (amiloride 10−4 M, ouabain 10−4 M, bumetanide 10−4 M), K+-free solutions, or organic solutes such as D-glucose 10 mM or DL-alanine 0.5 mM failed to affect V t or R t. Bafilomycin-A1 (3 to 5 μM) decreased V t by ≈ 40% and short-circuit current (I sc) by ≈ 50%, and decreased intracellular pH when applied from the basal side only, consistent with an inhibition of an electrogenic V-H+-ATPase located in the basal membrane. Gradients of H+ were detected by pH microelectrodes close to the basal aspect of the cells or within the basal extracellular labyrinth. The apical membrane is more conductive than the basal membrane, facilitating secretion of base (presumably HCO3 −), driven by the basal V-H+-ATPase. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Electrogenic H+ Transport and pH Gradients Generated by a V-H+-ATPase in the Isolated Perfused Larval Drosophila Midgut

Loading next page...
 
/lp/springer_journal/electrogenic-h-transport-and-ph-gradients-generated-by-a-v-h-atpase-in-8XdNv2OKGc
Publisher
Springer-Verlag
Copyright
Copyright © 2005 by Springer Science+Business Media, Inc.
Subject
Life Sciences; Human Physiology; Biochemistry, general
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-005-0774-1
Publisher site
See Article on Publisher Site

Abstract

A method for microperfusion of isolated segments of the midgut epithelium of Drosophila larvae has been developed to characterize cellular transport pathways and membrane transporters. Stereological ultrastructural morphometry shows that this epithelium has unusually long tight junctions, with little or no lateral intercellular volume normally found in most epithelia. Amplification of the apical and basal aspects of the cells, by ≈ 17-fold and ≈ 7-fold, respectively, predicts an almost exclusively transcellular transport system for solutes. This correlates with the high lumen-negative transepithelial potential (V t) of 38 to 45 mV and high resistance (R t) of 800 to 1400 Ω • cm2 measured by terminated cable analysis, in contrast to other microperfused epithelia like the renal proximal tubule. Several blockers (amiloride 10−4 M, ouabain 10−4 M, bumetanide 10−4 M), K+-free solutions, or organic solutes such as D-glucose 10 mM or DL-alanine 0.5 mM failed to affect V t or R t. Bafilomycin-A1 (3 to 5 μM) decreased V t by ≈ 40% and short-circuit current (I sc) by ≈ 50%, and decreased intracellular pH when applied from the basal side only, consistent with an inhibition of an electrogenic V-H+-ATPase located in the basal membrane. Gradients of H+ were detected by pH microelectrodes close to the basal aspect of the cells or within the basal extracellular labyrinth. The apical membrane is more conductive than the basal membrane, facilitating secretion of base (presumably HCO3 −), driven by the basal V-H+-ATPase.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Jan 1, 2005

References

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create lists to
organize your research

Export lists, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off