title: Antihypertensive and laxative effects by pharmacological inhibition of sodium-proton-exchanger subtype 3-mediated sodium absorption in the gut.
abstract: High intestinal sodium absorption is one mechanism of hypertension and constipation. The sodium-proton-exchanger subtype 3 (NHE3) is an important mediator of sodium absorption in the gut. SAR218034 (SAR) is an orally nonabsorbable specific NHE3 inhibitor. The effect of SAR (1 mg/kg per day in chow) on feces sodium excretion, systolic blood pressure via tail cuff, and gene expression of NHE3 in the gut were studied in senescent lean hypertensive rats (spontaneously hypertensive rats-lean, loaded with NaCl 0.7% in drinking water) and in hypertensive, obese, and hyperinsulinemic rats (spontaneously hypertensive rats-obese, not loaded with NaCl). In spontaneously hypertensive rats-lean, inhibition of intestinal NHE3 by SAR increased feces sodium excretion and reduced urinary sodium excretion, whereas absolute sodium balance and serum sodium concentration were not changed. This suggests reduced intestinal sodium absorption in SAR-treated animals and was associated with increased feces water content (58% versus 42% in placebo treated animals; P=0.0001) and reduction in systolic blood pressure from 222 ± 7 to 198 ± 2 mm Hg (P=0.0001). Angiotensin-converting enzyme inhibition by ramipril plus NHE3 inhibition resulted in an additive blood pressure-lowering effect. In spontaneously hypertensive rats-obese, SAR lowered systolic blood pressure but did not modify serum insulin or cholesterol levels. Gene expression of NHE3 was upregulated in the ileum and colon but not in the jejunum of SAR-treated rats. Reduction of intestinal sodium absorption by selective NHE3 inhibition in the gut reduces high blood pressure and increases feces water excretion. Intestinal NHE3 blockade could be a new treatment strategy for elderly patients suffering from high blood pressure and constipation.
authors.affiliation: Klinik für Innere Medizin III, Universitätsklinikum des Saarlandes, 66421 Homburg/Saar, Germany. dominik.linz@uks.eu
authors.forename: Dominik
authors.initials: D
authors.lastname: Linz
authors.forename: Klaus
authors.initials: K
authors.lastname: Wirth
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Linz
authors.forename: Hubert O O
authors.initials: HO
authors.lastname: Heuer
authors.forename: Wendelin
authors.initials: W
authors.lastname: Frick
authors.forename: Armin
authors.initials: A
authors.lastname: Hofmeister
authors.forename: Uwe
authors.initials: U
authors.lastname: Heinelt
authors.forename: Petra
authors.initials: P
authors.lastname: Arndt
authors.forename: Uwe
authors.initials: U
authors.lastname: Schwahn
authors.forename: Michael
authors.initials: M
authors.lastname: Böhm
authors.forename: Hartmut
authors.initials: H
authors.lastname: Ruetten
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology / Q000627:therapeutic use*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D041981:Gastrointestinal Tract / Q000187:drug effects* / Q000378:metabolism; D006973:Hypertension / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D011804:Quinolines / Q000494:pharmacology / Q000627:therapeutic use*; D017257:Ramipril / Q000494:pharmacology / Q000627:therapeutic use*; D051381:Rats; D011918:Rats, Inbred SHR; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D000959:Antihypertensive Agents; D011804:Quinolines; C578094:SAR218034; C000613387:Slc9a3 protein, rat; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers; D017257:Ramipril