| Autor: |
Buffenstein, R., Skinner, D. C., Yahav, S., Moodley, G. P., Cavaleros, M., Zachen, D., Ross, F. P., Pettifor, J. M. |
| Zdroj: |
Journal of Endocrinology; November 1991, Vol. 131 Issue: 2 p197-202, 6p |
| Abstrakt: |
The damara mole rat, Cryptomys damarensis, is a strictly subterranean dwelling herbivorous rodent that in its natural habitat has no access to any obvious source of cholecalciferol (D3). We examined the effects of D3supplementation, at physiological and supraphysiological doses, on calcium metabolism, plasma concentrations of calcium and alkaline phosphatase (ALP) and D3metabolites. Animals not receiving a D3supplement maintained normal plasma calcium concentrations. In addition, they exhibited a high apparent fractional mineral absorption efficiency (91%) and maintained a positive mineral flux. The serum concentration of 25-(OH)D3was undetectable (< 5 nmol/l) and that of 1,25-(OH)2D3was 41±10 pmol/l. Supplementation at a physiological dose of D3resulted in increased plasma concentrations of D3metabolites, food intake, apparent fractional absorption efficiency and apparent fractional retention efficiency. Despite the 1·8-fold increase in food intake, body mass remained constant suggesting that the enhanced energy intake was dissipated in catabolic processes. Plasma calcium and ALP concentrations were not significantly altered with physiological doses of D3. The group given supraphysiological doses of D3exhibited hypercalcaemia, increased creatinine concentrations and markedly increased ALP levels. These data indicate that a pathological response to D3intoxication occurred and that hepatic and renal excretory functions were impaired. It appears, therefore, that these animals function optimally at the low concentrations of D3metabolites found naturally. Supplementation at both physiological and supraphysiological doses of D3may disadvantage the damara mole rat.Journal of Endocrinology(1991) 131,197–202 |
| Databáze: |
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