Endogenous endothelins mediate increased distal tubule acidification induced by dietary acid in rats.
AUTOR(ES)
Wesson, D E
RESUMO
We examined if endogenous endothelins mediate the decreased HCO3 secretion and increased H+ secretion in in vivo-perfused distal tubules of rats fed dietary acid as (NH4)2SO4. Animals given (NH4)2SO4 drinking solution had higher endothelin-1 addition to renal interstitial fluid than those given distilled H2O (480+/-51 vs. 293+/-32 fmol g kidney wt(-1) min(-1), respectively, P < 0.03). (NH4)2SO4-ingesting animals infused with bosentan (10 mg/kg) to inhibit A- and B-type endothelin receptors had higher HCO3 secretion than baseline (NH4)2SO4 animals (-4.7+/-0.4 vs. -2.4+/-0.3 pmol mm(-1) min(-1), P < 0.01), but (NH4)2SO4 animals given a specific inhibitor of A-type endothelin receptors (BQ-123) did not (-2.0+/-0.2 pmol mm(-1) min(-1), P = NS vs. baseline). H+ secretion was lower in bosentan-infused compared with baseline (NH4)2SO4 animals (27.7+/-2.5 vs. 43.9+/-4.0 pmol mm(-1) min(-1), P < 0.03), but that for BQ-123-infused (NH4)2SO4 animals was not (42.9+/-4.2 pmol mm(-1) min(-1), P = NS vs. baseline). Bosentan had no effect on distal tubule HCO3 or H+ secretion in control animals. The data show that dietary acid increases endothelin-1 addition to renal interstitial fluid and that inhibition of B- but not A-type endothelin receptors blunts the decreased HCO3 secretion and increased H+ secretion in the distal tubule of animals given dietary acid. The data are consistent with endogenous endothelins as mediators of increased distal tubule acidification induced by dietary acid.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=508050Documentos Relacionados
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