Regulation of calcium metabolism ; its rhythmic variations
Perault-Staub, A.M.; Staub, J.F.
Comptes Rendus des Seances de la Societe de Biologie et de ses Filiales 173(2): 432-444
1979
ISSN/ISBN: 0037-9026 PMID: 159765 Document Number: 143805
For 3 weeks 2 groups of 40 male Wistar rats in metabolic cages with alternating 12 h light and dark were given a semisynthetic diet without or with calcium 0.7% during the dark period. Circadian changes in total and ionized Ca in blood and in plasma radioactivity after 100 mu Ci 45CaCl2 by vein were estimated. In both groups there was a biphasic pattern in total Ca changes during 24 h with a peak at 14 h, 4 h after feeding. In control rats maximum daily variation in Ca was 0.65 mg/100 ml. In rats deprived of Ca it increased from 1.2 mg after 2 weeks to 2.5 mg/100 ml after 3 weeks. Mean total and ionized Ca in blood after 3 weeks was 7.42 and 2.91 in deprived rats and 11.14 and 5.01 mg/100 ml in controls. Circadian changes in ionized Ca were directly related to total Ca. Circadian changes in plasma 45Ca were similar in both groups. They were similar in 40 rats given a diet with 1.5% Ca after parathyroidectomy to those of intact rats. In rats given a normal diet after parathyroidectomy, 45Ca did not fluctuate during the day.