Cross H S, Corradino R A, Peterlik M
Department of General and Experimental Pathology, University of Vienna Medical School, Austria.
Mol Cell Endocrinol. 1987 Sep;53(1-2):53-8. doi: 10.1016/0303-7207(87)90191-2.
1,25-Dihydroxyvitamin D3 (calcitriol), or vitamin D3 itself, when added to cultures of 20-day-old embryonic chick small intestine, stimulated sodium (Na+) uptake from the mucosal surface. The calcitriol-mediated increase in Na+ uptake appeared to be related to increased tight-junctional or paracellular permeability. Support for this conclusion was, first, that the uptake of other ions, potassium (K+) and rubidium (Rb+), with tight-junctional permeabilities greater than Na+, was also stimulated by calcitriol, and second, perturbation of cellular Na+ and K+ fluxes by inhibition of Na+/K+-ATPase activity did not affect calcitriol-stimulated Na+, K+, or Rb+ transport. Calcitriol stimulation of Na+ fluxes across the brush border as an alternate possibility is unlikely for the following reason: the calcium ionophore A23187, while mimicking the stimulatory action of calcitriol on calcium (Ca2+) uptake, reduced epithelial Na+ uptake. It is therefore suggested that calcitriol, by virtue of its effect on Ca2+ transport, reduces rather than stimulates cellular Na+ uptake.
1,25 - 二羟基维生素D3（骨化三醇）或维生素D3本身添加到20日龄鸡胚小肠培养物中时，会刺激黏膜表面对钠（Na⁺）的摄取。骨化三醇介导的Na⁺摄取增加似乎与紧密连接或细胞旁通透性增加有关。对这一结论的支持如下：首先，骨化三醇也刺激了紧密连接通透性大于Na⁺的其他离子，钾（K⁺）和铷（Rb⁺）的摄取；其次，抑制Na⁺/K⁺ - ATP酶活性对细胞Na⁺和K⁺通量的扰动并不影响骨化三醇刺激的Na⁺、K⁺或Rb⁺转运。骨化三醇刺激Na⁺通量穿过刷状缘作为另一种可能性不太可能，原因如下：钙离子载体A23187虽然模拟了骨化三醇对钙（Ca²⁺）摄取的刺激作用，但却降低了上皮细胞对Na⁺的摄取。因此，有人提出骨化三醇由于其对Ca²⁺转运的影响，会减少而不是刺激细胞对Na⁺的摄取。
