title: AT1 antagonism by eprosartan lowers heart rate variability and baroreflex gain.
abstract: BACKGROUND
  Blockade of the renin-angiotensin system (RAS) by ACE inhibitors has been demonstrated to reduce total mortality in cardiovascular diseases. This advantage was attributed in part to changes of autonomic cardiovascular control, exemplified by an increase of heart rate variability (HRV) and baroreflex gain (BRG). We sought to assess the effects of the angiotensin type 1 (AT1) receptor blocker eprosartan on HRV and BRG.
  
  
  METHODS
  In a double-blind randomized cross-over design 25 young males took eprosartan (600 mg/day) and placebo each for a period of 7 days with a wash-out period of at least 4 weeks in between. At the end of the intake phases simultaneous recordings of arterial blood pressure (AP; Finapres) and electrocardiogram (ECG) were taken. Power spectra of HRV and arterial blood pressure variability (APV) were calculated by fast Fourier transform (FFT) and served to calculate BRG. Ang-II levels were measured by radioimmunoassay.
  
  
  RESULTS
  Eprosartan tended to lower mean AP, it slightly increased heart rate (HR) (p<0.05), and markedly increased circulating Ang-II levels (p<0.01). Eprosartan diminished the total power of HRV (p<0.05) and the BRG (p<0.01). The low/high frequency (LF/HF) ratio of HRV and the APV were not altered.
  
  
  CONCLUSIONS
  AT1 antagonism by eprosartan lowers heart rate variability and baroreflex gain. We speculate that these findings are due to the marked increase in circulating angiotensin II (Ang II). Further studies are needed to clarify whether angiotensin type 1 (AT1) blockers with potential actions inside the blood-brain barrier (BBB) may have different effects on HRV and BRG.
authors.affiliation: Department of Medicine IV/Nephrology, University of Erlangen-Nuremberg, Krankenhausstrasse 12, 91054, Erlangen, Germany. karsten.heusser@gmx.de
authors.forename: Karsten
authors.initials: K
authors.lastname: Heusser
authors.forename: Jan
authors.initials: J
authors.lastname: Vitkovsky
authors.forename: Roland E
authors.initials: RE
authors.lastname: Schmieder
authors.forename: Hans P
authors.initials: HP
authors.lastname: Schobel
mesh_terms: D000179:Acrylates / Q000494:pharmacology*; D000328:Adult; D000804:Angiotensin II / Q000097:blood; D057911:Angiotensin Receptor Antagonists; D000959:Antihypertensive Agents / Q000494:pharmacology*; D017704:Baroreflex / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects; D004311:Double-Blind Method; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D008297:Male; D011446:Prospective Studies; D011863:Radioimmunoassay; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin / Q000502:physiology; D013876:Thiophenes
chemical_list: D000179:Acrylates; D057911:Angiotensin Receptor Antagonists; D000959:Antihypertensive Agents; D007093:Imidazoles; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin; D013876:Thiophenes; D000804:Angiotensin II; C068373:eprosartan