Gramicidin-Perforated Patch Analysis on HCO3 − Secretion Through a Forskolin-Activated Anion Channel in Rat Parotid Intralobular Duct Cells

Gramicidin-Perforated Patch Analysis on HCO3 − Secretion Through a Forskolin-Activated Anion... Forskolin-induced anion currents and depolarization were investigated to clarify the mechanism of HCO3 − secretion in the intralobular duct cells of rat parotid glands. Anion currents of the cells were measured at the equilibrium potential of K+, using a gramicidin-perforated patch technique that negligibly affects intracellular anion concentration. The forskolin-induced anion current was sustained and significantly (54%) suppressed by glibenclamide (200 μm), a blocker of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl− channel. The anion current was markedly suppressed by addition of 1 mm methazolamide, a carbonic anhydrase inhibitor, and removal of external HCO3 −. Forskolin depolarized the cells in the current-clamp mode. Addition of methazolamide and removal of external HCO3 − significantly decreased the depolarizing level. These results suggest that activation of anion channels (mainly the CFTR Cl− channel located in luminal membranes) and production of cytosolic HCO3 − induce the inward anion current and resulting depolarization. Inhibition of the Na+-K+-2Cl− cotransporter and the Cl−-HCO3 − exchanger had no significant effect on the current or depolarization, indicating that the uptake of Cl− via the Na+-K+-2Cl− cotransporter or the Cl−-HCO3 − exchanger is not involved in the responses. Taken together, we conclude that forskolin activates the outward movement (probably secretion) of HCO3 − produced intracellularly, but not of Cl− due to lack of active Cl− transport in parotid duct cells, and that the gramicidin-perforated patch method is very useful to analyze anion transport. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Gramicidin-Perforated Patch Analysis on HCO3 − Secretion Through a Forskolin-Activated Anion Channel in Rat Parotid Intralobular Duct Cells

Loading next page...
 
/lp/springer_journal/gramicidin-perforated-patch-analysis-on-hco3-secretion-through-a-ixLZdgoeH2
Publisher
Springer-Verlag
Copyright
Copyright © Inc. by 2001 Springer-Verlag New York
Subject
Life Sciences; Biochemistry, general; Human Physiology
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s002320010054
Publisher site
See Article on Publisher Site

Abstract

Forskolin-induced anion currents and depolarization were investigated to clarify the mechanism of HCO3 − secretion in the intralobular duct cells of rat parotid glands. Anion currents of the cells were measured at the equilibrium potential of K+, using a gramicidin-perforated patch technique that negligibly affects intracellular anion concentration. The forskolin-induced anion current was sustained and significantly (54%) suppressed by glibenclamide (200 μm), a blocker of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl− channel. The anion current was markedly suppressed by addition of 1 mm methazolamide, a carbonic anhydrase inhibitor, and removal of external HCO3 −. Forskolin depolarized the cells in the current-clamp mode. Addition of methazolamide and removal of external HCO3 − significantly decreased the depolarizing level. These results suggest that activation of anion channels (mainly the CFTR Cl− channel located in luminal membranes) and production of cytosolic HCO3 − induce the inward anion current and resulting depolarization. Inhibition of the Na+-K+-2Cl− cotransporter and the Cl−-HCO3 − exchanger had no significant effect on the current or depolarization, indicating that the uptake of Cl− via the Na+-K+-2Cl− cotransporter or the Cl−-HCO3 − exchanger is not involved in the responses. Taken together, we conclude that forskolin activates the outward movement (probably secretion) of HCO3 − produced intracellularly, but not of Cl− due to lack of active Cl− transport in parotid duct cells, and that the gramicidin-perforated patch method is very useful to analyze anion transport.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Mar 1, 2001

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 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
Access to DeepDyve database
Abstract access only
Unlimited access to over
18 million full-text articles
Print
20 pages/month
PDF Discount
20% off