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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
1
|
| pubmed:dateCreated |
1983-3-11
|
| pubmed:abstractText |
We investigated 3,3',5-tri-iodo-l-thyronine transport by human erythrocytes and by ;ghosts' prepared from these cells. Uptake of tri-iodothyronine by erythrocytes at 37 degrees C was time-dependent with a maximum reached after 60min. Tracer analysis after incubation for 1min revealed only one saturable binding site, with K(m) 128+/-19nm (mean+/-s.e.m.; n=7) and V(max.) 4.6+/-0.7pmol of tri-iodothyronine/min per 6x10(7) cells. After 10min incubation K(m) 100+/-16nm (n=10) was found with V(max.) 7.7+/-1.2pmol of tri-iodothyronine/10min per 6x10(7) cells. At 0 degrees C the uptake system is still active, with K(m) 132+/-26nm and V(max.) 1.8+/-0.3pmol of tri-iodothyronine/10min per 6x10(7) cells. The V(max.) with intact cells is 5-fold greater than the V(max.) with membranes derived from the same amount of cells when uptake studies are performed in media with similar free tri-iodothyronine concentrations. This indicates that at least 80% of tri-iodothyronine taken up by the intact erythrocytes enters the cell. This saturable uptake system can be inhibited by X-ray-contrast agents in a dose-dependent fashion. (+/-)-Propranolol, but not atenolol, has the same effect, indicating that the membrane-stabilizing properties of (+/-)-propranolol are involved. Furthermore, there is no inhibition by ouabain or vanadate, which indicates that tri-iodothyronine uptake is not dependent on the activity of Na(+)+K(+)-dependent adenosine triphosphatase. We have prepared erythrocyte ;ghosts', resealed after 2.5min with 0mm-, 2mm- or 4mm-ATP inside. Inclusion of ATP and integrity of the membrane of the erythrocyte ;ghosts' were verified on the basis of an ATP-concentration-dependent functioning of the Ca(2+) pump. No difference was found in the uptake of tri-iodothyronine by erythrocyte ;ghosts' with or without ATP included, indicating that uptake of tri-iodothyronine is not ATP-dependent. The following conclusions are drawn. (1) Tri-iodothyronine enters human erythrocytes. (2) There is only one saturable uptake system present for tri-iodothyronine, which is neither energy (i.e. ATP)-dependent nor influenced by the absence of an Na(+) gradient across the plasma membrane. This mode of uptake of tri-iodothyronine by human erythrocytes is in sharp contrast with that of rat hepatocytes, which uptake system is energy-dependent and ouabain-sensitive [Krenning, Docter, Bernard, Visser & Hennemann (1978) FEBS Lett.91, 113-116; Krenning, Docter, Bernard, Visser & Hennemann (1980) FEBS Lett.119, 279-282]. (3) X-ray-contrast agents inhibit tri-iodothyronine uptake by erythrocytes in a similar fashion to that by which they inhibit the uptake of tri-iodothyronine by rat hepatocytes [Krenning, Docter, Bernard, Visser & Hennemann (1982) FEBS Lett.140, 229-233].
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| pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-1260065,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-182449,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-199184,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-200236,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-26370,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-373606,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-384246,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-384247,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-384249,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-41520,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-4238381,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-486196,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-489611,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-491971,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-517049,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-6158047,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-6254310,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-7084465,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-7213706,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-7364937,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-7365316,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-7426039,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-7428942,
http://linkedlifedata.com/resource/pubmed/commentcorrection/7159396-977652
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| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:chemical | |
| pubmed:status |
MEDLINE
|
| pubmed:month |
Oct
|
| pubmed:issn |
0264-6021
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| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:day |
15
|
| pubmed:volume |
208
|
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
27-34
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| pubmed:dateRevised |
2009-11-18
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| pubmed:meshHeading |
pubmed-meshheading:7159396-Adenosine Triphosphate,
pubmed-meshheading:7159396-Biological Transport,
pubmed-meshheading:7159396-Calcium,
pubmed-meshheading:7159396-Energy Metabolism,
pubmed-meshheading:7159396-Erythrocyte Count,
pubmed-meshheading:7159396-Erythrocyte Membrane,
pubmed-meshheading:7159396-Erythrocytes,
pubmed-meshheading:7159396-Humans,
pubmed-meshheading:7159396-Kinetics,
pubmed-meshheading:7159396-Triiodothyronine,
pubmed-meshheading:7159396-Triiodothyronine, Reverse
|
| pubmed:year |
1982
|
| pubmed:articleTitle |
Evidence that the uptake of tri-iodo-L-thyronine by human erythrocytes is carrier-mediated but not energy-dependent.
|
| pubmed:publicationType |
Journal Article,
In Vitro,
Research Support, Non-U.S. Gov't
|