Menczel J, Singer L, Ophaug R H
Bone. 1987;8(2):91-4. doi: 10.1016/8756-3282(87)90076-7.
The synthetic metabolite of vitamin D3 [1 alpha(OH)D3] caused a significant plasma calcium elevation in rats only when dietary calcium was low. Animals given the low calcium diet (0.005%) had lower plasma parathyroid hormone (PTH) levels when the diet contained 1 alpha(OH)D3 and significantly higher levels than animals on a high calcium (0.95%) diet, with or without the vitamin. The nutritional stress of a low calcium diet without 1 alpha(OH)D3 resulted in a prolonged severe hypocalcemia and elevated serum PTH levels. A higher ash, phosphate, and calcium content was found in the bones of animals fed the high calcium diet, with no vitamin D3 that were given etidronate (EHDP). When animals received the same calcium diet with 1 alpha(OH)D3 supplementation, EHDP administration increased the percentage of bone ash but had no effect on ash weight. 1 alpha(OH)D3 or EHDP did not affect ash weight, dry fat free weight, and percentage of ash of bone of animals receiving a low calcium diet. The percentage of calcium and phosphorus in bone ash was similar among all groups, although the amounts per humerus were characteristically related to the calcium intake. There was approximately 20-25% less bone mineral and calcium and phosphorus in the humeri of low calcium intake animals than in animals provided an adequate dietary calcium.
维生素D3的合成代谢产物[1α(OH)D3]仅在膳食钙含量低时才会使大鼠血浆钙显著升高。给予低钙饮食（0.005%）的动物，当饮食中含有1α(OH)D3时，其血浆甲状旁腺激素（PTH）水平较低，且与无论有无该维生素的高钙（0.95%）饮食组动物相比，PTH水平显著更高。不含1α(OH)D3的低钙饮食所带来的营养应激会导致长期严重的低钙血症和血清PTH水平升高。在给予依替膦酸二钠（EHDP）的、喂食高钙饮食且无维生素D3的动物骨骼中，发现了更高的灰分、磷酸盐和钙含量。当动物接受添加了1α(OH)D3的相同钙饮食时，给予EHDP会增加骨灰百分比，但对灰分重量没有影响。1α(OH)D3或EHDP对接受低钙饮食的动物的灰分重量、去脂干重和骨骨灰百分比没有影响。尽管每组动物每肱骨中钙和磷的含量与钙摄入量有特定关系，但所有组骨骨灰中钙和磷的百分比相似。低钙摄入动物肱骨中的骨矿物质、钙和磷比摄入充足膳食钙的动物大约少20 - 25%。
