Transport Pathways for Therapeutic Concentrations of Lithium in Rat Liver

Transport Pathways for Therapeutic Concentrations of Lithium in Rat Liver Although both amiloride- and phloretin-sensitive Na+/Li+ exchange activities have been reported in mammalian red blood cells, it is still unclear whether or not the two are mediated by the same pathway. Also, little is known about the relative contribution of these transport mechanisms to the entry of therapeutic concentrations of Li+ (0.2–2 mm) into cells other than erythrocytes. Here, we describe characteristics of these transport systems in rat isolated hepatocytes in suspension. Uptake of Li+ by hepatocytes, preloaded with Na+ and incubated in the presence of ouabain and bumetanide, comprised three components. (a) An amiloride-sensitive component, with apparent K m 1.2 mm Li+, V max 40 μmol · (kg dry wt · min)−1, showed increased activity at low intracellular pH. The relationship of this component to the concentration of intracellular H+ was curvilinear suggesting a modifier role of [H+] i . This system persisted in Na+-depleted cells, although with apparent K m 3.8 mm. (b) A phloretin-sensitive component, with K m 1.2 mm, V max 21 μmol · (kg · min)−1, was unaffected by pH but was inactive in Na+-depleted cells. Phloretin inhibited Li+ uptake and Na+ efflux in parallel. (c) A residual uptake increased linearly with the external Li+ concentration and represented an increasing proportion of the total uptake. The results strongly suggest that the amiloride-sensitive and the phloretin-sensitive Li+ uptake in rat liver are mediated by two separate pathways which can be distinguished by their sensitivity to inhibitors and intracellular [H+]. The Journal of Membrane Biology Springer Journals

Transport Pathways for Therapeutic Concentrations of Lithium in Rat Liver

Loading next page...
Copyright © Inc. by 1999 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