Intestinal phosphate absorption: influence of vitamin D and non-vitamin D factors.
Intestinal phosphate absorption: influence of vitamin D and non-vitamin D factors.
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DOI：
10.1152/ajpgi.1986.250.3.g369
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发表时间：
1986-03
期刊：
影响因子：
--
通讯作者：
D. B. Lee;M. Walling;N. Brautbar
中科院分区：
文献类型：
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作者：
D. B. Lee;M. Walling;N. Brautbar
在没有电化学梯度的情况下，测定了无机磷酸盐(P)在体外大鼠空肠中的转运。年轻的维生素d缺乏(d)大鼠对P的吸收活跃，而正常的非维生素d缺乏成年大鼠的P分泌活跃，这表明肠道P转运的调节机制依赖于年龄，但不依赖于维生素d。1,25-二羟基维生素D3 [1,25(OH)2D3]刺激粘膜到浆膜P通量（Jm----s），而不影响浆膜到粘膜P通量（Js----m），导致d大鼠净P吸收（Jnet）进一步增加，正常成年大鼠净P分泌减少，证实了该激素对P吸收的作用。然后，我们检测了增加细胞外（缓冲）P浓度[P]对d大鼠空肠125 (OH) 2d3刺激的P活性吸收的影响。在[P]为0.024、0.24和2.4 mM时，1,25(OH)2D3持续刺激Jm----s而不影响Jm---- m，导致Jnet增加。然而，在7.5 mM时[P]，不再观察到125 (OH)2D3对Jm----s的刺激作用。此外，在此[P]，在d和1,25(OH) 2d3补充的大鼠中，Js----m都超过了Jm----s，在两个治疗组中将活性P吸收转化为活性P分泌。这些观察结果表明，局部机制，如运输肠细胞的环境[P]，参与肠P吸收的调节。最后，研究了饲粮P剥夺对d大鼠P吸收的影响，分别是补充或不补充维生素D3或1,25(OH)2D3。（摘要删节250字）
The transport of inorganic phosphate (P) was measured in the absence of electrochemical gradients across rat jejunum in vitro. Active P absorption was demonstrated in young, vitamin D-deficient (-D) rats, whereas active P secretion was found in normal, non-vitamin D-deficient adult rats, suggesting regulation of intestinal P transport by age-dependent but vitamin D-independent mechanisms. 1,25-Dihydroxyvitamin D3 [1,25(OH)2D3] stimulated mucosal-to-serosal P flux (Jm----s) without affecting serosal-to-mucosal P flux (Js----m), causing further increases in net P absorption (Jnet) in -D rats and reduction in net P secretion in normal adult rats, confirming a previously described role of this hormone on P absorption. We then examined the effect of increasing extracellular (buffer) P concentration [P] on this 1,25(OH)2D3-stimulated active P absorption in jejunum from -D rats. At [P] of 0.024, 0.24, and 2.4 mM, 1,25(OH)2D3 consistently stimulated Jm----s without affecting Js----m, causing an increment in Jnet. At 7.5 mM [P], however, this Jm----s stimulatory effect of 1,25(OH)2D3 was no longer observed. Moreover, at this [P] the Js----m exceeded Jm----s in both -D and 1,25(OH)2D3-repleted rats, converting the active P absorption into active P secretion in both treatment groups. These observations suggest the participation of local mechanisms, such as the ambient [P] of the transporting enterocytes, in the regulation of intestinal P absorption. Finally, the influence of dietary P deprivation on P absorption was studied in -D rats, with or without either vitamin D3 or 1,25(OH)2D3 repletion.(ABSTRACT TRUNCATED AT 250 WORDS)