Oxygen-dependent 1,25-dihydroxycholecalciferol-induced calcium ion transport in rat intestine.
Oxygen-dependent 1,25-dihydroxycholecalciferol-induced calcium ion transport in rat intestine.
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大鼠肠道中氧依赖性 1,25-二羟基胆钙化醇诱导的钙离子转运。
DOI：
10.1042/bj1940178
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发表时间：
1981
期刊：
影响因子：
--
通讯作者：
DeLuca,HF
中科院分区：
文献类型：
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作者：
Kendrick,NC;Kabakoff,B;DeLuca,HF
大鼠十二指肠盘对O2依赖的钙摄取已被用于1，25-二羟胆钙化醇诱导的肠道钙转运的改良测定。虽然在这种自由漂浮圆盘实验中，肌肉和粘膜表面都暴露了出来，但穿过肌肉表面的钙离子内流很小，不依赖O2或维生素D，可以被减去。在测定前剥夺动物9-14小时的食物可增加约75%的O2依赖摄取。维生素D缺乏大鼠摄取氧依赖钙的半饱和值分别为0.8 mM-Ca~(2+)和0.5 mM-Ca~(2+)，给予1，25-二羟基胆钙醇的大鼠半饱和值分别为0.9 mM-Ca~(2+)和1.5 mm-Ca~(2+)。维生素D缺乏的大鼠摄取钙的最大速率为6.7nmoL/cm2/min(摄食)至7.0nmoL/cm2/min(食物缺乏)，1，25-二羟基胆钙醇处理的大鼠摄取钙的最大速度为16.7nmoL/cm2/min(摄食)至29nmoL/cm2/min(禁食)。用1.0 mM-Ca~(2+)预先孵育5分钟和15分钟后，经维生素D处理的大鼠十二指肠组织对O2依赖的钙摄取比从维生素D缺乏的动物组织中增加约3倍。钙离子载体A23187对O2依赖的摄取没有显著影响或抑制，而不是增加，这取决于浓度。2微克/g剂量的放线菌素D可抑制维生素D缺乏和维生素D处理的大鼠肠道对O2依赖的摄取，分别抑制58%和80%，在测定前3个半小时给药。
O2-dependent CA2+ uptake by rat duodenal discs has been characterized and used in a revised assay for 1,25-dihydroxycholecalciferol-induced intestinal Ca2+ transport. Although both muscle and mucosal surfaces are exposed in this free-floating-disc assay, the Ca2+ influx across the muscle surface is small, not O2- or vitamin D-dependent, and can be subtracted out. Depriving the animals of food for 9-14 h before assay increases the O2-dependent uptake by about 75%. Half-saturation values for O2-dependent Ca2+ uptake as determined with this assay are: 0.8mM-Ca2+ (fed) and 0.5mM-Ca2+ (food-deprived) for vitamin D-deficient rats, and 0.9mM-Ca2+ (fed) and 1.5mM-Ca2+ (food-deprived) for rats dosed with 1,25-dihydroxycholecalciferol. The maximum velocity of uptake varies from 6.7nmol of Ca2+ per cm2/min (fed) to 7.0nmol of Ca2+ per cm2/min (food-deprived) for vitamin D-deficient rats and 16.7nmol of Ca2+ per cm2/min (fed) to 29 nmol of Ca2+ per cm2/min (food-deprived) for 1,25-dihydroxycholecalciferol-treated rats. By using a 5 min preincubation and 15 min incubation with 1.0mM-Ca2+, duodenal tissue taken from vitamin D-treated rats shows about a 3-fold increase in O2-dependent Ca2+ uptake when compared with tissue taken from vitamin D-deficient animals. The calcium ionophore A23187, depending on concentration, either has no significant effect on or inhibits the O2-dependent uptake, rather than increasing it. Actinomycin D, at a dose of 2 micrograms/g, inhibits the O2-dependent uptake in intestinal discs from both vitamin D-deficient and vitamin D-treated rats by 58 and 80% respectively, when administeredin vivo3 1/2 h before assay.