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Experimentelle Untersuchungen zur Lokalisation der enteralen Calciumresorption

  • Roland Halbritter
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Zusammenfassung

  1. 1.

    Der Ort der enteralen Calciumresorption der Ratte wurde unter Verwendung von45Calcium untersucht. 20, 40 und 60 min nach oraler Applikation einer45CaCl2-Lösung wurden die Ratten getötet, der Dünndarm in 8 Segmente unterteilt und der45Ca-Gehalt der Darmwand bestimmt. Die45Calciumbestimmung erfolgte nach einer neuen Methode: Auflösen des Gewebes in wäßriger Kalilauge, Mischen mit einer speziellen Scintillationsflüssigkeit und Messen der45Ca Aktivität durch die Flüssigkeits-Scintillations-Zählung.

     
  2. 2.

    Experiment I (36 Ratten) ergab unter normalen Passagebedingungen eine maximale Calciumresorption im proximalen und mittleren Ileum — den Orten langer Kontaktzeit.

     
  3. 3.

    In Experiment II (24 Ratten) wurde durch einen experimentell gesetzten Dünndarmverschluß (auf verschiedener Höhe vor der Ileocöcalklappe) ein Weitertransport des Darminhaltes verhindert. Die Kontaktzeit zwischen Darminhalt und Darmwand in den proximalen Segmenten wurde dadurch bedeutend verlängert. Es zeigte sich, daß auf diese Weise die jeweilig ausgiebigste enterale Calciumresorption in den dem Verschluß vorgelagerten Dünndarmabschnitten erfolgte, zumeist im Jejunum oder auch im Duodenum.

     

Die Experimente an der Ratte beweisen, daß für das Calcium, das eine relativ geringe enterale Resorptionsquote aufweist,die Kontaktzeit ausschlaggebend für den Ort der enteralen Resorption ist.

Schlüsselwörter

Calciumresorption Enterale Kontaktzeit Enteraler Resorptionsort 

Experiments to investigate the localisation of intestinal calcium absorption

Summary

  1. 1.

    The localisation of intestinal calcium absorption in the rat was studied by means of radioactive45Calcium. Rats were killed 20, 40, and 60 min after oral administration of45CaCl2-solution.45Ca-activity of the intestinal wall was determined after having divided the entire small intestine into 8 segments.45Ca was determined by a new procedure: maceration of tissue in watery potassium-hydroxide, mixture with a special scintillation fluid, and determination of the activity by liquid-scintillation-counting.

     
  2. 2.

    Experiment I (36 rats) demonstrates a maximal calcium absorption in the proximal and middle portion of the ileum — under normal conditions of intestinal transit.

     
  3. 3.

    Experiment II (24 rats): The intestinal transit was experimentally stopped by clipping at various levels proximal to the ileocoecal valve thus prolonging the time of contact in intestinal segments before the stop considerably. It could be demonstrated that calcium absorption took place maximally in segments before the experimental stop mostly jejunum or duodenum.

     

These experiments in the rat serve as evidence that for calcium which is absorbed relatively slowly by the small intestine thetime of contact plays a dominating role for the localisation of intestinal absorption.

Key-words

Calcium absorption Intestinal time of contact Site of intestinal absorption 

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Copyright information

© Springer-Verlag 1971

Authors and Affiliations

  • Roland Halbritter
    • 1
    • 2
  1. 1.Pathologisches Institut der Universität ZürichSchweiz
  2. 2.I. Medizinische Klinik der UniversitätMünchen 15Deutschland

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