title: Endothelin contributes to blunted renal autoregulation observed with a high-salt diet.
abstract: Autoregulation of renal blood flow (RBF) is an essential function of the renal microcirculation that has been previously shown to be blunted by excessive dietary salt. Endogenous endothelin 1 (ET-1) is increased following a high-salt (HS) diet and contributes to the control of RBF but the differential effects of ET-1 on renal microvessel autoregulation in response to HS remain to be established. We hypothesized that a HS diet increases endothelin receptor activation in normal Sprague-Dawley rats and blunts autoregulation of RBF. The role of ET-1 in the blunted autoregulation produced by a HS diet was assessed in vitro and in vivo using the blood-perfused juxtamedullary nephron preparation and anesthetized rats, respectively. Using highly selective antagonists, we observed that blockade of either ETA or ETB receptors was sufficient to restore normal autoregulatory behavior in afferent arterioles from HS-fed rats. Additionally, normal autoregulatory behavior was restored in vivo in HS-fed rats by simultaneous ETA and ETB receptor blockade, whereas blockade of ETB receptors alone showed significant improvement of normal autoregulation of RBF. Consistent with this observation, autoregulation of RBF in ETB receptor-deficient rats fed HS was similar to both ETB-deficient rats and transgenic control rats on normal-salt diets. These data support the hypothesis that endogenous ET-1, working through ETB and possibly ETA receptors, contributes to the blunted renal autoregulatory behavior in rats fed a HS diet.
authors.affiliation: Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia;
authors.forename: Robert C
authors.initials: RC
authors.lastname: Fellner
authors.affiliation: Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia; Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Zhengrong
authors.initials: Z
authors.lastname: Guan
authors.affiliation: Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia; Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Anthony K
authors.initials: AK
authors.lastname: Cook
authors.affiliation: Section of Experimental Medicine, Department of Medicine, Medical College of Georgia, Georgia Regents University, Augusta, Georgia; and Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: David M
authors.initials: DM
authors.lastname: Pollock
authors.affiliation: Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia; Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama einscho@uab.edu.
authors.forename: Edward W
authors.initials: EW
authors.lastname: Inscho
mesh_terms: D000818:Animals; D001160:Arterioles / Q000187:drug effects; D004032:Diet; D065130:Endothelin A Receptor Antagonists / Q000494:pharmacology; D065131:Endothelin B Receptor Antagonists / Q000494:pharmacology; D016232:Endothelins / Q000378:metabolism*; D006706:Homeostasis / Q000187:drug effects*; D008297:Male; D008833:Microcirculation; D009399:Nephrons / Q000187:drug effects; D009842:Oligopeptides / Q000627:therapeutic use; D010456:Peptides, Cyclic / Q000627:therapeutic use; D010880:Piperidines / Q000627:therapeutic use; D051381:Rats; D017207:Rats, Sprague-Dawley; D012079:Renal Circulation; D012982:Sodium, Dietary / Q000009:adverse effects*
chemical_list: D065130:Endothelin A Receptor Antagonists; D065131:Endothelin B Receptor Antagonists; D016232:Endothelins; D009842:Oligopeptides; D010456:Peptides, Cyclic; D010880:Piperidines; D012982:Sodium, Dietary; C086539:BQ 788; C072247:cyclo(Trp-Asp-Pro-Val-Leu)
keywords: BQ-123; BQ-788; ETA receptors; ETB receptors; afferent arterioles