Abstract
Six-week-old male Wistar rats weighing about 130g were given normal, calcium (Ca)-free and mineral-free diets for seven days, and then bled from the tail vein at 0, 0.25, 0.5, 1, 2, 4, and 8h after ovenight food deprivation (for 16h). The rats were then orally administered 0, 20, 40, or 100mg Ca/rat, and the intestines were removed immediately after decapitation 8h later. When 20mg Ca was supplied orally, the plasma Ca level reached maximum after about 1h in rats given the normal diet, and after about 2h in the rats given the Ca-free and mineral-free diets, although the levels were higher in the order normal, Ca-free, and mineral-free. After the 40-mg dose, the plasma Ca level became maximal after about 2h irrespective of diet, the highest level being attained in rats given the mineral-free diet, followed by those given the Ca-free and normal diets. With the 100-mg dose, the plasma Ca concentration was markedly increases for the first 30min after administration, irrespective of diet, and then decreased slightly in rats given the normal diet and increased slightly in rats given the Ca-free diet, although the level in the rats given the mineral-free diet increased linearly. All rats given the mineral-free diet died within 24h after Ca supply. The amounts of Ca remaining in the intestines were generally inversely correlated with the plasma Ca concentration, irrespective of diet. Kinetic analysis of Ca movement suggested that the apparent volume of distribution was closely related to the observed results.
