Mechanisms Underlying Regulation of a Barium -sensitive K+ Conductance by ATP in Single Proximal Tubule Cells Isolated from Frog Kidney

Mechanisms Underlying Regulation of a Barium -sensitive K+ Conductance by ATP in Single Proximal... K+ channels play an important role in pump-leak coupling and volume regulation in the renal proximal tubule. Previous experiments have identified a barium-sensitive K+ conductance (G Ba) in proximal tubule cells isolated from frog kidneys. In this paper we examine the regulation of G Ba by ATP. G Ba was measured in single cells isolated from frog kidney using the whole-cell patch-clamp technique. G Ba was activated by 2 mM intracellular ATP. This activation was enhanced by inhibition of protein kinase C and attenuated by inhibition of protein kinase A, indicating reciprocal regulation by these kinases. Activation by ATP was reduced in the presence of a hypertonic bath solution, suggesting that cell swelling was required. However, after activation to steady-state, G Ba was not sensitive to cell-volume changes. Hypotonic shock-induced volume regulation was inhibited by barium and quinidine, inhibitors of G Ba. The effect of maximal inhibitory concentrations of barium and quinidine on volume regulation was similar and addition of both blockers together did not augment the inhibitory response. G Ba was also activated by ADP, via a mechanism dependent on the presence of Mg2+. However, the responses to ADP and ATP were not additive, suggesting that these nucleotides may share a common mechanism of activation. The regulation of G Ba by ATP was biphasic, with a half-maximal activating concentration of 0.89 mM and a half maximal inhibitory concentration of 6.71 mM. The sensitivity to nucleotides suggests that G Ba may be regulated by the metabolic state of the cell. Furthermore, the sensitivity to solution osmolality, coupled with the blocker profile of inhibition of volume regulation, suggests that G Ba could play a role in volume regulation. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Mechanisms Underlying Regulation of a Barium -sensitive K+ Conductance by ATP in Single Proximal Tubule Cells Isolated from Frog Kidney

Loading next page...
 
/lp/springer_journal/mechanisms-underlying-regulation-of-a-barium-sensitive-k-conductance-ylqdXTKM0C
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/s00232-005-0745-8
Publisher site
See Article on Publisher Site

Abstract

K+ channels play an important role in pump-leak coupling and volume regulation in the renal proximal tubule. Previous experiments have identified a barium-sensitive K+ conductance (G Ba) in proximal tubule cells isolated from frog kidneys. In this paper we examine the regulation of G Ba by ATP. G Ba was measured in single cells isolated from frog kidney using the whole-cell patch-clamp technique. G Ba was activated by 2 mM intracellular ATP. This activation was enhanced by inhibition of protein kinase C and attenuated by inhibition of protein kinase A, indicating reciprocal regulation by these kinases. Activation by ATP was reduced in the presence of a hypertonic bath solution, suggesting that cell swelling was required. However, after activation to steady-state, G Ba was not sensitive to cell-volume changes. Hypotonic shock-induced volume regulation was inhibited by barium and quinidine, inhibitors of G Ba. The effect of maximal inhibitory concentrations of barium and quinidine on volume regulation was similar and addition of both blockers together did not augment the inhibitory response. G Ba was also activated by ADP, via a mechanism dependent on the presence of Mg2+. However, the responses to ADP and ATP were not additive, suggesting that these nucleotides may share a common mechanism of activation. The regulation of G Ba by ATP was biphasic, with a half-maximal activating concentration of 0.89 mM and a half maximal inhibitory concentration of 6.71 mM. The sensitivity to nucleotides suggests that G Ba may be regulated by the metabolic state of the cell. Furthermore, the sensitivity to solution osmolality, coupled with the blocker profile of inhibition of volume regulation, suggests that G Ba could play a role in volume regulation.

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