AII can also affect salt and water homeostasis through

AII can also affect salt and water homeostasis through BMS-354825 its actions on renal Na reabsorption. In addition, AII stimulates aldosterone production by the adrenal gland that is a major regulator of renal and intestinal Na transport. The present studies demonstrate that AII has direct effects on intestinal epithelial Na transport that are consistent with its desired effect to increase fluid absorption. Angiotensin II increases NHE3 gene transcription Although AII has been noted to increase small intestinal Na absorption previously, the present studies provide a more definitive analysis, demonstrating that this is due to stimulated exocytosis of the apical trans porter NHE3 and later increased expression of this trans porter. In contrast, NHE2 activity is not regulated by AII.

NHE2 has a lesser contribution to intestinal Na transport NHE3 gene, resulting in increases in total NHE3 protein abundance. This second phase is associated with addi tional apical membrane insertion of NHE3 and enhanced Na absorptive capacity. The effects of AII on intestinal transport could be either indirect and/or direct and the present studies demonstrate that direct effects occur. When AII was given intravascularly, it stimulated the enteric nervous system which could affect intestinal elec trolyte transport. However, when AII was added to in vitro preparations of rat small intestine serosally, it stim ulated Na transport, suggesting that AII was acting directly on epithelial cells similar to present results in mouse jejunum. Adding further support to this possibil ity, AII binds with high affinity to intestinal enterocyte membranes.

More recent studies of porcine jeju activationstimulationphospholipase epoxygenationactivationarachidonic and is regulated differently by agonist activated sec ond messenger pathways. The actions of AII on intestinal epithelial Na transport appear to involve both acute and chronic effects. Acutely, AII rapidly stimulates insertion of NHE3 into the apical membrane which increases Na absorption. However, over time, AII stimulates transcriptional activation of the num found both types of the AII receptor, however full thickness intestine was used for analysis which contains both epithelial and non epithelial cell components. Luminal/brush border type I and II AII receptors have been functionally demonstrated in intestine where lumi nal AII, through the type I receptor, inhibits apical Na dependent glucose transport.

A similar finding of brush border type I AII receptor regulates apical glucose uptake in LLC PK porcine kidney cells. The effects on apical sodium transport were not measured in these stud ies of intestinal and renal brush border membranes. The intestine possesses a complete renin angiotensin sys tem that appears to have local autocrine and para crine effects. Anacetrapib Angiotensinogen, renin and the angiotensin converting enzyme are all expressed in the intestine, as well as both types of AII receptors.

Leave a Reply

Your email address will not be published. Required fields are marked *

*

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>