Key role of aldosterone and pericryptal myofibroblast growth in colonic permeability.
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.
Cristià
Esther
E
Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain.
Moretó
Miquel
M
Naftalin
Richard J
RJ
D000222:Adaptation, Physiological; D000450:Aldosterone / Q000494:pharmacology / Q000502:physiology*; D000804:Angiotensin II / Q000494:pharmacology / Q000502:physiology*; D003106:Colon / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects*; D032389:Myocytes, Smooth Muscle / Q000378:metabolism / Q000502:physiology; D010539:Permeability; D012982:Sodium, Dietary / Q000008:administration & dosage / Q000378:metabolism* / Q000493:pharmacokinetics
D012982:Sodium, Dietary; D000804:Angiotensin II; D000450:Aldosterone