Sodium-dependent and -independent Choline Uptake by Type II Epithelial Cells from Rat Lung

Sodium-dependent and -independent Choline Uptake by Type II Epithelial Cells from Rat Lung The uptake of 3H-labeled choline by a suspension of isolated type II epithelial cells from rat lung has been studied in a Ringer medium. Uptake was linear for 4 min at both 0.1 μm and 5.0 μm medium choline; at 5 μm, only 10% of the label was recovered in a lipid fraction. Further experiments were conducted at the low concentration (0.1 μm), permitting characterization of the properties of high-affinity systems. Three fractions of choline uptake were detected: (i) a sodium-dependent system that was totally inhibited by hemicholinium-3 (HC-3); (ii) a sodium-independent uptake, when Na+ was replaced by Li+, K+ or Mg2+, inhibited by HC-3; (iii) a residual portion persisting in the absence of Na+ and unaffected by HC-3. Choline uptake was sigmoidally related to the medium Na+ concentration. Kinetic properties of the uptake of 0.1 μm 3H-choline in the presence and absence of medium Na+ were examined in two ways. (a) Inhibition by increasing concentrations of unlabeled choline (0.5–100 μm) was consistent with the presence of two Michaelis-Menten-type systems in the presence of Na+; a Na+-dependent portion (a mean of 0.52 of the total) had a K m for choline of 1.5 μm while K m in the absence of Na+ (Li+ substituting) was 18.6 μm. (b) Inhibition by HC-3 (0.3–300 μm) gave Ki values of 1.7 μm and 5.0 μm HC-3 for the Na+-dependent and -independent fractions. The apparent K m of the Na+-dependent uptake is lower than that reported previously for lung-derived cells and is in the range of the K m values reported for high-affinity, Na+-dependent choline uptake by neuronal cells. The Journal of Membrane Biology Springer Journals

Sodium-dependent and -independent Choline Uptake by Type II Epithelial Cells from Rat Lung

Loading next page...
Copyright © Inc. by 1998 Springer-Verlag New York
Life Sciences; Biochemistry, general; Human Physiology
Publisher site
See Article on Publisher Site

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

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