Caco-2 Cell Line Used as an In Vitro Model to Study Cadmium Accumulation in Intestinal Epithelial Cells

Caco-2 Cell Line Used as an In Vitro Model to Study Cadmium Accumulation in Intestinal Epithelial... 109Cd uptake was studied using the highly differentiated TC7 clone of Caco-2 cells as a model of human enterocyte function. Intracellular accumulation of 0.3 μm 109Cd involved a rapid and a slow uptake phase, which resulted in complete equilibration (t ½= 17.3 ± 1.3 min) with an apparent in-to-out distribution ratio (α e ) of 11.6 ± 0.8. The amplitude of the rapid phase (U 0) and the rate of the slow phase (V) were similarly reduced in the less differentiated PF11 clone, but comparable α e values were observed at equilibrium. In both clones, the t ½ and α e values increased and decreased, respectively, upon addition of unlabeled Cd to the uptake media. In TC7 cells, 109Cd uptake at 1 min (U 1) was unaffected by Ca concentrations four order of magnitude in excess, but both U 0 and V demonstrated similar sensitivities to unlabeled Cd, Zn and sulfhydryl-reactive agents. Only U 0 disappeared when EDTA was present in the wash solutions. U 1 showed saturation kinetics and the data were found compatible with a model assuming rapid initial Cd binding and transport through a unique transport protein (K m = 3.8 ± 0.7 μm). Cd efflux kinetics demonstrated partial reversibility in EDTA-containing solutions, suggesting that the taken up Cd might be both tightly and loosely bound to intracellular binding sites. However, the displacement of 109Cd measured at 65 min failed to reveal this heterogeneity: the data were found compatible with a model equation assuming the presence of one class of high-capacity high-affinity binding sites. We conclude that a slow-transport fast-intracellular binding mechanism of Cd uptake best accounts for these results and that Cd transport most likely involves a carrier-type of protein unrelated to Ca absorption. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Caco-2 Cell Line Used as an In Vitro Model to Study Cadmium Accumulation in Intestinal Epithelial Cells

Loading next page...
 
/lp/springer_journal/caco-2-cell-line-used-as-an-in-vitro-model-to-study-cadmium-UnKNvwm4R5
Publisher
Springer-Verlag
Copyright
Copyright © Inc. by 1997 Springer-Verlag New York
Subject
Life Sciences; Biochemistry, general; Human Physiology
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s002329900241
Publisher site
See Article on Publisher Site

Abstract

109Cd uptake was studied using the highly differentiated TC7 clone of Caco-2 cells as a model of human enterocyte function. Intracellular accumulation of 0.3 μm 109Cd involved a rapid and a slow uptake phase, which resulted in complete equilibration (t ½= 17.3 ± 1.3 min) with an apparent in-to-out distribution ratio (α e ) of 11.6 ± 0.8. The amplitude of the rapid phase (U 0) and the rate of the slow phase (V) were similarly reduced in the less differentiated PF11 clone, but comparable α e values were observed at equilibrium. In both clones, the t ½ and α e values increased and decreased, respectively, upon addition of unlabeled Cd to the uptake media. In TC7 cells, 109Cd uptake at 1 min (U 1) was unaffected by Ca concentrations four order of magnitude in excess, but both U 0 and V demonstrated similar sensitivities to unlabeled Cd, Zn and sulfhydryl-reactive agents. Only U 0 disappeared when EDTA was present in the wash solutions. U 1 showed saturation kinetics and the data were found compatible with a model assuming rapid initial Cd binding and transport through a unique transport protein (K m = 3.8 ± 0.7 μm). Cd efflux kinetics demonstrated partial reversibility in EDTA-containing solutions, suggesting that the taken up Cd might be both tightly and loosely bound to intracellular binding sites. However, the displacement of 109Cd measured at 65 min failed to reveal this heterogeneity: the data were found compatible with a model equation assuming the presence of one class of high-capacity high-affinity binding sites. We conclude that a slow-transport fast-intracellular binding mechanism of Cd uptake best accounts for these results and that Cd transport most likely involves a carrier-type of protein unrelated to Ca absorption.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Jul 1, 1997

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