Palytoxin Acts on Na+,K+-ATPase but not Nongastric H+,K+-ATPase

Palytoxin Acts on Na+,K+-ATPase but not Nongastric H+,K+-ATPase Palytoxin (PTX) opens a pathway for ions to pass through Na,K-ATPase. We investigate here whether PTX also acts on nongastric H,K-ATPases. The following combinations of cRNA were expressed in Xenopus laevis oocytes: Bufo marinus bladder H,K-ATPase α2- and Na,K-ATPase β2-subunits; Bufo Na,K-ATPase α1- and Na,K-ATPase β2-subunits; and Bufo Na,K-ATPase β2-subunit alone. The response to PTX was measured after blocking endogenous Xenopus Na,K-ATPase with 10 μm ouabain. Functional expression was confirmed by measuring 86Rb uptake. PTX (5 nm) produced a large increase of membrane conductance in oocytes expressing Bufo Na,K-ATPase, but no significant increase occurred in oocytes expressing Bufo H,K-ATPase or in those injected with Bufo β2-subunit alone. Expression of the following combinations of cDNA was investigated in HeLa cells: rat colonic H,K-ATPase α1-subunit and Na,K-ATPase β1-subunit; rat Na,K-ATPase α2-subunit and Na,K-ATPase β2-subunit; and rat Na,K-ATPase β1- or Na,K-ATPase β2-subunit alone. Measurement of increases in 86Rb uptake confirmed that both rat Na,K and H,K pumps were functional in HeLa cells expressing rat colonic HKα1/NKβ1 and NKα2/NKβ2. Whole-cell patch-clamp measurements in HeLa cells expressing rat colonic HKα1/NKβ1 exposed to 100 nm PTX showed no significant increase of membrane current, and there was no membrane conductance increase in HeLa cells transfected with rat NKβ1- or rat NKβ2-subunit alone. However, in HeLa cells expressing rat NKα2/NKβ2, outward current was observed after pump activation by 20 mm K+ and a large membrane conductance increase occurred after 100 nm PTX. We conclude that nongastric H,K-ATPases are not sensitive to PTX when expressed in these cells, whereas PTX does act on Na,K-ATPase. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Palytoxin Acts on Na+,K+-ATPase but not Nongastric H+,K+-ATPase

Loading next page...
 
/lp/springer_journal/palytoxin-acts-on-na-k-atpase-but-not-nongastric-h-k-atpase-G2mL6IWwFg
Publisher
Springer-Verlag
Copyright
Copyright © 2007 by Springer Science+Business Media, LLC
Subject
Life Sciences; Human Physiology ; Biochemistry, general
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-007-9040-1
Publisher site
See Article on Publisher Site

Abstract

Palytoxin (PTX) opens a pathway for ions to pass through Na,K-ATPase. We investigate here whether PTX also acts on nongastric H,K-ATPases. The following combinations of cRNA were expressed in Xenopus laevis oocytes: Bufo marinus bladder H,K-ATPase α2- and Na,K-ATPase β2-subunits; Bufo Na,K-ATPase α1- and Na,K-ATPase β2-subunits; and Bufo Na,K-ATPase β2-subunit alone. The response to PTX was measured after blocking endogenous Xenopus Na,K-ATPase with 10 μm ouabain. Functional expression was confirmed by measuring 86Rb uptake. PTX (5 nm) produced a large increase of membrane conductance in oocytes expressing Bufo Na,K-ATPase, but no significant increase occurred in oocytes expressing Bufo H,K-ATPase or in those injected with Bufo β2-subunit alone. Expression of the following combinations of cDNA was investigated in HeLa cells: rat colonic H,K-ATPase α1-subunit and Na,K-ATPase β1-subunit; rat Na,K-ATPase α2-subunit and Na,K-ATPase β2-subunit; and rat Na,K-ATPase β1- or Na,K-ATPase β2-subunit alone. Measurement of increases in 86Rb uptake confirmed that both rat Na,K and H,K pumps were functional in HeLa cells expressing rat colonic HKα1/NKβ1 and NKα2/NKβ2. Whole-cell patch-clamp measurements in HeLa cells expressing rat colonic HKα1/NKβ1 exposed to 100 nm PTX showed no significant increase of membrane current, and there was no membrane conductance increase in HeLa cells transfected with rat NKβ1- or rat NKβ2-subunit alone. However, in HeLa cells expressing rat NKα2/NKβ2, outward current was observed after pump activation by 20 mm K+ and a large membrane conductance increase occurred after 100 nm PTX. We conclude that nongastric H,K-ATPases are not sensitive to PTX when expressed in these cells, whereas PTX does act on Na,K-ATPase.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Jul 17, 2007

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 12 million articles from more than
10,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Unlimited reading

Read as many articles as you need. Full articles with original layout, charts and figures. Read online, from anywhere.

Stay up to date

Keep up with your field with Personalized Recommendations and Follow Journals to get automatic updates.

Organize your research

It’s easy to organize your research with our built-in tools.

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