Effect of Age on Calcium Uptake in Isolated Duodenum Cells: Role of 1,25-Dihydroxyvitamin D3
| Autor: | C. T. Liang, J. Barnes, S. Takamato, B. Sacktor |
|---|---|
| Rok vydání: | 1989 |
| Předmět: |
Aging
medicine.medical_specialty Duodenum Cell Population chemistry.chemical_element In Vitro Techniques Calcium Muscle Development Sucrase chemistry.chemical_compound Endocrinology Calcitriol Glucoside Reference Values Internal medicine medicine Vitamin D and neurology Animals education Calcifediol education.field_of_study Methylglucosides Muscle Smooth Rats Inbred Strains Rats Kinetics medicine.anatomical_structure chemistry Efflux |
| Zdroj: | Endocrinology. 124:2830-2836 |
| ISSN: | 1945-7170 0013-7227 |
| DOI: | 10.1210/endo-124-6-2830 |
| Popis: | Uptake of Ca2+ in cells isolated from rat duodenum declined in the senescent rats. This age-related change was not due to an alteration in the rate of Ca2+ efflux or in the size of the cell. The decrease appeared specific, as alpha-methyl glucoside uptake was not altered. Cell population, as monitored by sucrase activity for villus cells, was not different between duodenal cells isolated from 6- and 24-month-old rats. Kinetic analysis shows the Vmax, the apparent maximum uptake capacity, decreased in the cells from senescent rats whereas the Km, the apparent affinity to Ca2+, was unchanged. Serum levels of 25-hydroxyvitamin D (25OHD) and 1,25-dihydroxyvitamin D [1,25-(OH)2D] were determined as a function of age; the levels of 25OHD were not significantly different in 3-, 6-, 12-, and 24-month-old rats. On the other hand, serum 1,25-(OH)2D decreased throughout the age range studied. Since duodenal Ca2+ uptake is closely regulated by 1,25-(OH)2D3, we tested the hypothesis that low serum 1,25-(OH)2D in the senescent rats may have contributed to the decline in duodenal Ca2+ uptake. In vivo administration of 1,25-(OH)2D3 to senescent rats significantly enhanced Ca2+ uptake activity in the isolated duodenal cells. After 1,25-(OH)2D3 treatment, Ca2+ uptake activity in cells isolated from senescent rats was only slightly less than that in cells from adult rats. We conclude that duodenal Ca2+ uptake declined in the senescent rats, and this age-related change was most likely due to the low serum level of 1,25-(OH)2D and not the result of a decrease in any duodenal response to 1,25-(OH)2D3. |
| Databáze: | OpenAIRE |
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