Regulation of the Slow Vacuolar Channel by Luminal Potassium: Role of Surface Charge

Regulation of the Slow Vacuolar Channel by Luminal Potassium: Role of Surface Charge Voltage-dependent activation of slow vacuolar (SV) channels has been studied on isolated patches from red beet (Beta vulgaris L.) vacuoles. Isoosmotic variation of vacuolar K+ from 10 to 400 mM in Ca2+-free solutions at the vacuolar side shifted the SV channel activation threshold to more positive voltages. The effect of K+ could be mimicked by additions of choline or N-methyl D-glucamine and could be explained by unspecific screening of the negative surface charge. Fitting the dependence of voltage shift on K+ concentration to the Gouy-Chapman model yields a surface charge density of 0.36 ± 0.05 e−/nm2. Negative surface potential also tended to increase the local concentration of permeable ions (K+), resulting in anomalously high single-channel conductance, ∼200 pS in 10 mM KCl. An increase of ionic strength due to addition of impermeable cations greatly reduced the unitary conductance. Large positive shift of the SV channel voltage dependence, caused by physiological (0.5 mM) free vacuolar Ca2+, was partly ameliorated by increasing luminal K+. We interpreted these results as follows: K+ induced a reduction of surface potential, hence i) causing a positive shift of the voltage dependence and ii) a dilution of Ca2+ in the membrane vicinity, thus reducing the inhibitory effect of vacuolar Ca2+ and causing a negative shift of the SV channel voltage dependence, with a sum of the two shifts being negative. The Journal of Membrane Biology Springer Journals

Regulation of the Slow Vacuolar Channel by Luminal Potassium: Role of Surface Charge

Loading next page...
Copyright © 2005 by Springer Science+Business Media, Inc.
Life Sciences; Human Physiology; Biochemistry, general
Publisher site
See Article on Publisher Site


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

Monthly Plan

  • Read unlimited articles
  • Personalized recommendations
  • No expiration
  • Print 20 pages per month
  • 20% off on PDF purchases
  • Organize your research
  • Get updates on your journals and topic searches


Start Free Trial

14-day Free Trial

Best Deal — 39% off

Annual Plan

  • All the features of the Professional Plan, but for 39% off!
  • Billed annually
  • No expiration
  • For the normal price of 10 articles elsewhere, you get one full year of unlimited access to articles.



billed annually
Start Free Trial

14-day Free Trial