Aldosterone synthase knockout mouse as a model for sodium-induced endothelial sodium channel up-regulation in vascular endothelium.
Recently, a novel feedforward activation of the endothelial epithelial sodium channel (ENaC) [endothelial sodium channel (EnNaC)] by sodium was reported that counteracts ENaC function in kidney. In the absence of aldosterone, a rise in extracellular sodium (>145 mM) increases EnNaC surface abundance, thereby stiffening the cortex of vascular endothelial cells (ECs) in vitro. The latter reduces the release of NO-the hallmark of endothelial dysfunction. Here, we test whether high extracellular sodium per se increases EnNaC expression and cortical stiffness in an aldosterone synthase (Cyp11b2)-deficient (AS(-/-)) mouse model. Therefore, we employed in situ ECs of ex vivo aorta preparations from wild-type (WT) and AS(-/-). EnNaC surface expression (-16%) and cortical stiffness (-22%) were reduced in AS(-/-), compared with WT, whereas NO secretion was exclusively detectable in AS(-/-). EnNaC inhibition with benzamil decreased stiffness in both, while mineralocorticoid receptor antagonism diminished stiffness only in the WT. In the absence of aldosterone, high sodium (150 mM) increased EnNaC surface expression ex vivo (plus 19%) and cortical stiffness ex vivo (plus 41%) and in vivo (plus 44%). Application of aldosterone adjusted the stiffness of AS(-/-) to the WT level. We conclude that high sodium per se determines EnNaC expression and consequently endothelial cortical nanomechanics, thus likely contributing to endothelial dysfunction.
*Institute of Physiology II, University of Munster, Munster, Germany; and Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany.
Pia
P
Jeggle
*Institute of Physiology II, University of Munster, Munster, Germany; and Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany.
Verena
V
Hofschröer
*Institute of Physiology II, University of Munster, Munster, Germany; and Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany.
Martina
M
Maase
*Institute of Physiology II, University of Munster, Munster, Germany; and Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany.
Marko
M
Bertog
*Institute of Physiology II, University of Munster, Munster, Germany; and Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany kusche@uni-muenster.de.
Kristina
K
Kusche-Vihrog
D000450:Aldosterone / Q000494:pharmacology; D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D019405:Cytochrome P-450 CYP11B2 / Q000172:deficiency / Q000378:metabolism*; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D053503:Epithelial Sodium Channels / Q000378:metabolism; D005260:Female; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D000451:Mineralocorticoid Receptor Antagonists / Q000494:pharmacology; D023421:Models, Animal; D009569:Nitric Oxide / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects
D053503:Epithelial Sodium Channels; D000451:Mineralocorticoid Receptor Antagonists; C013407:benzamil; D009569:Nitric Oxide; D000450:Aldosterone; D000584:Amiloride; D012964:Sodium; D019405:Cytochrome P-450 CYP11B2
ENaC; atomic force microscopy; mineralocorticoid receptor