On the molecular mechanism of intestinal calcium transport.
On the molecular mechanism of intestinal calcium transport.
复制标题
肠道钙转运的分子机制研究.
DOI：
10.1007/978-1-4684-9111-1_5
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发表时间：
1989
影响因子：
--
通讯作者：
Fullmer,CS
中科院分区：
文献类型：
--
作者：
Wasserman,RH;Fullmer,CS
血液中的钙浓度，大概类似于进化过程中古海洋中的钙浓度，是一个相对稳定的生物"常数"，在正常个体中平均约为2.5 mM（10 mg/dl）。血钙浓度的维持主要是钙调节激素的功能，即甲状旁腺激素（PTH）、降钙素和维生素D激素1，25-二羟基维生素D3（1，25（OH）2D3）（Bronner & Coburn，1982; Lawson，1978）。参与全身钙稳态的主要器官系统是肠、肾和骨骼。在低钙血症期间分泌的甲状旁腺激素发挥三种主要作用：（a）增加骨吸收，（B）减少肾小管对磷酸盐的重吸收和（c）刺激肾25（OH）D3 - 1-羟化酶系统合成1，25（OH）2D3。维生素D激素：（a）与甲状旁腺激素协同作用，增加骨吸收过程，（B）增加肠对钙的吸收，（c）增加远端肾小管对钙的重吸收（图1）。甲状旁腺激素和1，25（OH）2D3的双重作用的净效应是确保维持血液Ca 2+的正常水平。维生素D和1，25（OH）2D3也会刺激肠道对磷酸盐的吸收（Wasserman & Taylor，1973; Peterlik & Wasserman，1978）。另一方面，降钙素在高钙血症期间分泌，通过抑制骨细胞骨吸收，使血液Ca2+水平降至正常范围内（Mac Intyre，1986）。
The calcium concentration in blood, presumably similar to the calcium concentration in ancient seas during evolution, is a relatively stable biological “constant”, averaging about 2.5 mM (10 mg/dl) in the normal individual. The maintenance of blood calcium concentrations is primarily the function of the calcium regulating hormones, namely, parathyroid hormone (PTH), calcitonin and the vitamin D hormone, 1,25-dihydroxyvitamin D3(1,25(OH)2D3) (Bronner & Coburn, 1982; Lawson, 1978). The main organ systems involved in systemic calcium homeostasis are the intestine, kidney and skeleton. Parathyroid hormone, secreted during periods of hypocalcemia, exerts three main effects: (a) increases bone resorption, (b) decreases phosphate reabsorption by renal tubules and (c) stimulates the synthesis of l,25(OH)2D3by the renal 25(OH)D3–1-hydroxylase system. The vitamin D hormone: (a) synergizing with parathyroid hormone, increases the bone resorptive process, (b) increases the intestinal absorption of calcium, and (c) increases the reabsorption of calcium by the distal renal tubules (Figure 1). The net effect of the dual action of parathyroid hormone and 1,25(OH)2D3is to assure that normal levels of blood Ca2+are maintained. Phosphate absorption by the intestine is also stimulated by vitamin D and 1,25(OH)2D3(Wasserman & Taylor, 1973; Peterlik & Wasserman, 1978). Calcitonin, on the other hand, is secreted during periods of hypercalcemia and, by inhibiting osteoclastic bone resorption, brings blood Ca2+levels down to within the normal range (Mac Intyre, 1986).