Cristià Esther, Moretó Miquel, Naftalin Richard J
Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain.
J Pediatr Gastroenterol Nutr. 2007 Dec;45 Suppl 2:S127-30. doi: 10.1097/MPG.0b013e31812e680b.
When sodium intake diminishes, both the kidney and distal colon contribute directly to sodium homeostasis. In response to a diet with low amounts of sodium, the body hormonal profile changes to produce different effects on crypt-colon permeability and absorption and in the pericryptal sheath surrounding distal colonic crypts. This adaptation produces an increase in Na absorption, a decreased crypt-wall permeability, and an activation of the growth of pericryptal myofibroblasts. The separate roles of the 2 main hormones implicated in the process, aldosterone and angiotensin II, until now have been unclear. Experiments conducted on adrenalectomized rats on low- and high-sodium diets, implanted with osmotic pumps perfusing either aldosterone or angiotensin II, allow us to discriminate between the effects of these hormones. In the distal colon, aldosterone acts as a trophic agent on the myofibroblasts layer and is the key hormone controlling colonic permeability, but angiotensin II alone has no discernable direct role in the process.
当钠摄入量减少时，肾脏和远端结肠都直接参与钠稳态的维持。针对低钠饮食，身体的激素谱会发生变化，从而对隐窝 - 结肠的通透性、吸收以及远端结肠隐窝周围的隐窝周鞘产生不同影响。这种适应性变化会使钠吸收增加、隐窝壁通透性降低，并激活隐窝周肌成纤维细胞的生长。此前，该过程中涉及的两种主要激素醛固酮和血管紧张素II的各自作用尚不清楚。在低钠和高钠饮食条件下对肾上腺切除的大鼠进行实验，通过植入渗透泵灌注醛固酮或血管紧张素II，使我们能够区分这些激素的作用。在远端结肠中，醛固酮对肌成纤维细胞层起营养作用，是控制结肠通透性的关键激素，但单独的血管紧张素II在该过程中没有明显的直接作用。
