Nonselective Cation Channels in Endothelial Cells Derived from Human Umbilical Vein

Nonselective Cation Channels in Endothelial Cells Derived from Human Umbilical Vein (i) We have used a combined patch-clamp and fura-2 fluorescence technique to characterize a nonselective cation channel (NSC) in Ea.hy926 (EA) cells, an endothelial cell line derived from human umbilical vein. (ii) Stimulation with ATP, histamine and bradykinin activated slowly and with a long delay after application of the agonist, a nonselective cation current (I NSC) which is time- and voltage-independent. The permeability sequence for cations was P Na > P Cs >> P NMDG , P Ca . In the absence of external Ca2+ and at rather high concentrations, La3+ and Gd3+ blocked I NSC . (iii) Single channel analysis revealed that ATP activates in the cell-attached configuration a nonselective cation channel with a conductance of approximately 24 pS and a permeation sequence identical to that of the macroscopic current. The channel activity disappeared after membrane excision. (iv) Activation of NSC required physiological intracellular Ca2+ levels (100 nm or higher). All agonists failed to activate NSC if cytosolic Ca2+ ([Ca2+] i ) was lowered by 10 mm BAPTA. Clamping internal Ca2+ at 1 μm sometimes (8 out of 17 cells) spontaneously activated I NSC in the absence of any additional stimulus. (v) Application of 2,5-di-tert-butylhydroquinone and internal perfusion of inositol 1,4,5-trisphosphate also activated I NSC . The phospholipase C inhibitor, U-73122 inhibited I NSC and the sustained Ca2+ plateau during agonist stimulation whereas the inactive analogue, U-73343 had no effect. (vi) These results indicate NSC may act as a Ca2+ entry pathway in endothelium. [Ca2+] i and inositol 1,4,5-trisphosphate play a role in the activation cascade of NSC, and possibly also store depletion. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Nonselective Cation Channels in Endothelial Cells Derived from Human Umbilical Vein

Loading next page...
 
/lp/springer_journal/nonselective-cation-channels-in-endothelial-cells-derived-from-human-5gzajMYTLJ
Publisher
Springer-Verlag
Copyright
Copyright © Inc. by 1999 Springer-Verlag New York
Subject
Life Sciences; Biochemistry, general; Human Physiology
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/PL00005898
Publisher site
See Article on Publisher Site

Abstract

(i) We have used a combined patch-clamp and fura-2 fluorescence technique to characterize a nonselective cation channel (NSC) in Ea.hy926 (EA) cells, an endothelial cell line derived from human umbilical vein. (ii) Stimulation with ATP, histamine and bradykinin activated slowly and with a long delay after application of the agonist, a nonselective cation current (I NSC) which is time- and voltage-independent. The permeability sequence for cations was P Na > P Cs >> P NMDG , P Ca . In the absence of external Ca2+ and at rather high concentrations, La3+ and Gd3+ blocked I NSC . (iii) Single channel analysis revealed that ATP activates in the cell-attached configuration a nonselective cation channel with a conductance of approximately 24 pS and a permeation sequence identical to that of the macroscopic current. The channel activity disappeared after membrane excision. (iv) Activation of NSC required physiological intracellular Ca2+ levels (100 nm or higher). All agonists failed to activate NSC if cytosolic Ca2+ ([Ca2+] i ) was lowered by 10 mm BAPTA. Clamping internal Ca2+ at 1 μm sometimes (8 out of 17 cells) spontaneously activated I NSC in the absence of any additional stimulus. (v) Application of 2,5-di-tert-butylhydroquinone and internal perfusion of inositol 1,4,5-trisphosphate also activated I NSC . The phospholipase C inhibitor, U-73122 inhibited I NSC and the sustained Ca2+ plateau during agonist stimulation whereas the inactive analogue, U-73343 had no effect. (vi) These results indicate NSC may act as a Ca2+ entry pathway in endothelium. [Ca2+] i and inositol 1,4,5-trisphosphate play a role in the activation cascade of NSC, and possibly also store depletion.

Journal

The Journal of Membrane BiologySpringer Journals

Published: May 1, 1999

There are no references for this article.

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