Calcium transport by rat duodenal villus and crypt basolateral membranes.
Calcium transport by rat duodenal villus and crypt basolateral membranes.
复制标题
大鼠十二指肠绒毛和隐窝基底外侧膜的钙转运。
DOI：
10.1152/ajpgi.1987.252.2.g170
复制
发表时间：
1987
期刊：
影响因子：
--
通讯作者：
Weiser,MM
中科院分区：
文献类型：
--
作者：
Walters,JR;Weiser,MM
连续分离大鼠十二指肠细胞，得到富含绒毛和隐窝细胞的级分。从每个级分中，制备了富含基底外侧的膜囊泡，并研究了 ATP 依赖性钙吸收。钙吸收对温度敏感，受到钒酸盐和 A23187 的抑制，并且在缺乏维生素 D 的动物中较低。在正常动物中，绒毛尖端的钙转运大约是隐窝细胞部分基底外侧膜的两倍，尽管钙摄取的亲和力相似（Km = 0.3 microM）。在维生素 D 缺乏的动物中，隐窝到绒毛的梯度降低，并且在所有部分中，钙转运与正常动物的隐窝相似或更低。缺乏维生素 D 的动物补充 1,25-二羟基胆钙化醇 6 小时后，外翻肠囊的钙转运显着增加；然而，基底外侧钙转运仅在中绒毛部分显着增加，而在绒毛尖端部分没有看到变化。因此，维生素 D 对于十二指肠绒毛细胞中基底外侧膜钙泵活性的增加似乎是必需的，但并非维生素 D 缺乏的大鼠中的所有细胞都能对 1,25-二羟基胆钙化醇产生反应。
Rat duodenal cells were isolated sequentially to give fractions enriched for villus and crypt cells. From each of these fractions, basolateral-enriched membrane vesicles were prepared and ATP-dependent calcium uptake was studied. Calcium uptake was sensitive to temperature, was inhibited by vanadate and by A23187, and was lower in vitamin D-deficient animals. In normal animals, calcium transport was approximately twofold greater in villus-tip than in crypt cell-fraction basolateral membranes though the affinity of the uptake for calcium was similar (Km = 0.3 microM). In vitamin D-deficient animals, the crypt-to-villus gradient was reduced, and in all fractions, calcium transport was similar to or lower than that in the crypts of normal animals. Six hours after vitamin D-deficient animals were repleted with 1,25-dihydroxycholecalciferol, a significant increase in calcium transport by everted gut sacs was present; however, basolateral calcium transport was significantly increased in only the mid-villus fractions, and no change was seen in the villus-tip fractions. Thus vitamin D appears necessary for the development of increased basolateral membrane calcium pump activity in duodenal villus cells, but not all cells in vitamin D-deficient rats are able to respond to 1,25-dihydroxycholecalciferol.