title: Eplerenone blocks nongenomic effects of aldosterone on the Na+/H+ exchanger, intracellular Ca2+ levels, and vasoconstriction in mesenteric resistance vessels.
abstract: There is increasing evidence for rapid nongenomic effects of aldosterone. Aldosterone has been demonstrated to alter intracellular pH and calcium in isolated cells. However, few studies have correlated these effects with aldosterone-mediated physiological responses. Therefore, we studied rapid effects of aldosterone on vascular reactivity, intracellular Ca2+, and pH in resistance vessels. Furthermore, we explored whether the new antimineralocorticoid drug eplerenone could effectively block nongenomic aldosterone-mediated effects. The vasoconstrictor action of aldosterone was examined directly by determining the diameter of small resistance mesenteric vessels (160-200 microm resting diameter), simultaneously with intracellular pH or Ca2+. Aldosterone (10 nm) caused a rapid constriction of resistance vessels (8.1% +/- 1.0% reduction in the diameter below control conditions, P < 0.05). Aldosterone potentiated phenylephrine-mediated constriction in small and large mesenteric vessels. Aldosterone induced a rapid increase of intracellular Ca2+ and cellular alkalinization. Vasoconstrictor action of aldosterone and nongenomic effects on the sodium-proton exchanger (NHE1) activity or intracellular Ca2+ responses was abolished by eplerenone. The vasoconstrictor response of aldosterone was related to phosphatidylinositol 3-kinase (PI3-K): the hormone decreased protein kinase B phosphorylation; pharmacological inhibition of PI3-K (10 microm LY294002 or 1 microm wortmannin) increased arterial contractility. Inhibitors of ERK 1/2 phosphorylation (15 microm PD98059) had no effect on aldosterone-mediated vasoconstriction. Inhibition of protein kinase C with 1 microm bi-sindolylmaleimide I and/or inhibition of NHE1 with 100 microm amiloride abolished aldosterone vasoconstrictor action of resistance mesenteric arteries. We conclude that aldosterone-mediated increase in vascular tone is related to a nongenomic mechanism that involves protein kinase C, PI3-K, and NHE1 activity. Eplerenone is an effective blocker of nongenomic effects of aldosterone in vascular tissue.
authors.affiliation: Laboratory of Cellular and Molecular Physiology, Faculty of Medicine, University Los Andes, S. Carlos Apoquindo 2200, Las Condes, 6782468 Santiago, Chile. lmichea@uandes.cl
authors.forename: Luis
authors.initials: L
authors.lastname: Michea
authors.forename: Ana M
authors.initials: AM
authors.lastname: Delpiano
authors.forename: Catalina
authors.initials: C
authors.lastname: Hitschfeld
authors.forename: Lorena
authors.initials: L
authors.lastname: Lobos
authors.forename: Sergio
authors.initials: S
authors.lastname: Lavandero
authors.forename: Elisa T
authors.initials: ET
authors.lastname: Marusic
mesh_terms: D000450:Aldosterone / Q000378:metabolism*; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D002867:Chromones / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D000077545:Eplerenone; D005419:Flavonoids / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007211:Indoles / Q000494:pharmacology; D008297:Male; D008301:Maleimides / Q000494:pharmacology; D008638:Mesenteric Arteries / Q000187:drug effects*; D000451:Mineralocorticoid Receptor Antagonists; D009025:Morpholines / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017207:Rats, Sprague-Dawley; D000074082:Sodium-Hydrogen Exchanger 1; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism*; D013148:Spironolactone / Q000031:analogs & derivatives* / Q000494:pharmacology*; D013997:Time Factors; D014661:Vasoconstriction; D000077191:Wortmannin; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D000450:Aldosterone; D000730:Androstadienes; D002118:Calcium; D002867:Chromones; D004791:Enzyme Inhibitors; D000077545:Eplerenone; D005419:Flavonoids; D007211:Indoles; D008301:Maleimides; D000451:Mineralocorticoid Receptor Antagonists; D009025:Morpholines; D010656:Phenylephrine; D019869:Phosphatidylinositol 3-Kinases; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D000074082:Sodium-Hydrogen Exchanger 1; D017923:Sodium-Hydrogen Exchangers; D013148:Spironolactone; D000077191:Wortmannin; D048051:p38 Mitogen-Activated Protein Kinases; C452850:Slc9a1 protein, rat; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C070515:bisindolylmaleimide I; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one