ISSN:
1432-1912
Keywords:
Tl+-ions
;
Excretion
;
Mucosal epithelium
;
Small intestine
;
Large intestine
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary 1. The movement of Tl+-ions was investigated on both isolated non blood-perfused jejunal and ileal segments as well as on stripped colon segments in vitro of rats. 2. After having administered radioactively labeled 204Tl-(Tl2SO4) on either the mucosal or the serosal side of these preparations only, a preferential direction of the movement of Tl+-ions from the serosal to the mucosal side was observed. In jejunal segments, the 204Tl-radioactivity at the mucosal side reached a concentration equilibrium with the concentration administered at the serosal side of the preparations. In colon segments a concentration gradient of more than 2 was established between the mucosal and the serosal side. In ileal segments the concentration of 204Tl-radioactivity in the mucosal fluid reached roughly 80% of that administered at the serosal side. 3. The amount taken up into the intestinal tissue is much higher after having administered the 204Tl-radioactivity from the serosal side than from the mucosal side. This holds true for jejunal ileal, and colonic segments. 4. In equilibrium experiments of non-everted colonic segments which were incubated on either side with the same 204Tl-concentrations the net transfer of 204Tl was determined directly. After a delay of 60 min the net transfer of 204Tl follows the rapid uptake into the intestinal tissue. 5. The net transfer as well as the tissue content of 204Tl decreases with increasing concentrations. From concentrations of 204Tl-ions of 5×10-5M on, no concentration gradient between the mucosal and the serosal side could be established. 6. The net transfer of 204Tl depends highly on temperature. At 29°C a diminished concentration gradient of the 204Tl between the mucosal and the serosal fluid was observed. At 25°C no concentration gradient could be established. The content of 204Tl in tissue, however, was not affected by this decrease of temperature. 7. The net transfer of 204Tl is nearly doubled by an increase of the K+-concentration at the mucosal side from 4.5 (normal) up to 72 mM, whereas the change of the 204Tl-content in tissue was statistically not significant. A decrease, however, of the net transfer of 204Tl is the consequence of an increased K+-concentration at the serosal side. In these segments the 204Tl content in tissue is decreased by 16% at the highest concentration of K+-ions.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00518485
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