The absorption of cMcium and strontium from the gastrointestinal tract was determined in lactating rats between the 14th and 16th day of lactation using radioactive isotopes of calcium (45Ca and 47Ca) and strontium (ssSr) both in the in vivo and in the in vitro experiments.The absorbed dose of strontium and calcium (expressed as the sum of the radioactivity retained in the skeleton of the mother and litter and eliminated in urine) was determined in lactating animals after a two-day oral administration of radioactive isotopes. The absorbed radioactive dose in lactating animals was found to be 3 times as high for calcium and twice as high for strontium as in controls. The total amount o~ calcium and strontium absorbed from the intestinal tract of lactating animals was, however, about 6 and 4 times as high as in controls due to a two-fold increase in food consumption.The total passage of calcium and strontium from the mucosal to the serosal side of the everted duodenal sac in lactating animals was 2.8 and 3.4 times as high for strontium and calcium respectively as in controls. The active transport of calcium was also about twice normal in lactating anima]s.The authors discuss the possible morphological basis for these findings. Key words." Intestinal absorption Lactation --Calcimn and Strontium metabolism.L'absorption du calcium et du strontium par l'intestin a 6t6 d6termin6e chez les rattes allaitantes entre le lge et le ]6e jour de la lactation, en utilisant les isotopes radioactifs du calcium (~sCa et 47Ca) et du strontium (s~Sr) dans les exp6riences in vivo ainsi que dans les exp6riences in vitro.La dose de strontium et de calcium absorb@ (exprim@ comme la somme de la radioactivit6 retenue dans le squelette de la mbxe et de la port6e et 61imin6e par l'urine) a 6t6 6valuge chez les animaux allaitants aprbs une application oralc d'isotopes radioactifs pendant 2 jours. On a trouv6 que la dose radioactive de calcium et de strontium absorb@ 6tail 3 et 2 lois plus 61ev@ chez les rattes allaitantes que chez les animaux t6moins. N6ammoins, la quantit6 totale de Ca et de Sr absorb~s au niveau du tractus intestinal des rattes allaitantes est environ 6 et 4 fois plus 61ev@ ~ cause d'une consommation de nourriture qui est deux fois plus grande chez les rattes allaitantes que ehez les animaux t6moins.Chez les rattes allaitantes, le passage total du calcium et du strontium du c6t6 muqueux au e6te s6reux du s~c duod6nal retourn6 6tait 2.8 fois plus Nev@, pour le strontium et 3.4 fois plus 61ev@ pour le calcium. Le transport actif du calcium 6tail aussi d'environ deux fois plus 61ev6 ehez les rattes allaitantes.Les auteurs discutent de la base morphologique possible de ces r6sultats.Die Absorption von Calcium und Strontium aus dem gastrointestinalen Trakt bei sgugenden Ratten zwischen dem 14. und 16. Tag der Lactation wurde mit Hilfe yon radioaktiven Isotopen yon Calcium (4sCa und 47Ca) und von Strontium (ssSr) sowohl in vivo als auch in vitro bestimmt.

The effect of iron on manganese transport through, and its retention in, the duodenal wall was studied in 5-week-old female albino rats. Animals were fed only cow’s milk supplemented with different doses of ferrous sulphate (0.60–19.0 mg Fe/100 ml) for 3 days before killing. Manganese transport was studied in vitro by the method of ‘everted gut sac’. In all rats fed milk supplemented with iron the manganese transport through, and its retention within, the intestinal wall was significantly lower than when no iron was given (0.001 > p < 0.001). The suppression of both the transfer and intestinal retention of manganese suggests a saturation effect produced by iron which levels off above 5 mg Fe/100 ml milk.

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