Abstract
The greater intestinal absorption of calcium (Ca) in younger than in older rats could be associated with increased lumen-to-mucosa(LM) and/or decreased mucosa-to-lumen(ML) flux of Ca. We determined net absorption (NA) of Ca in the intestine of 1, 2, 3, 4 and 6 week old rats. The jejunum + ileum was perfused in situ with a solution containing per liter 3.4 mmole of 40Ca, 145 mmole of NaCl, and 20 mg of Phenol Red. Tracer 45Ca was added to determine LM flux. ML flux was calculated as the difference between LM flux and NA. As expected NA of Ca (μmoles/g dry weight/hr) was greater in suckling than in older rats (Mean±SE; 1wk, 18±4; 3wk, 16±3; 6wk, 3±2). LM flux was around twice NA and greater in the suckling rats (1wk, 45±5; 3wk, 28±3; 6wk, 8±1). ML flux was also greater in the suckling rats (1wk, 27±3; 3wk, 12±2; 6wk, 5±2). Thus the increased net Ca absorption in the suckling than in the older rats seemed to be the result of markedly enhanced unidirectional fluxes of Ca across the intestinal mucosa. These findings could be explained on the basis of greater permeability of the intestinal mucosa to Ca in suckling than in older rats. However, it is possible that the activity of the mechanisms involved in transport of Ca decreases with age in rats.
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Younoszai, M., Ranshaw, J. DEVELOPMENT OF CALCIUM TRANSPORT IN THE JEJUNUM + ILEUM OF RATS. Pediatr Res 11, 414 (1977). https://doi.org/10.1203/00006450-197704000-00267
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DOI: https://doi.org/10.1203/00006450-197704000-00267
