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Published on: January 31, 2019

Antihypertensive agents have different ability to modulate arterial pressure and heart rate variability in 2K1C rats

Fernando Nobre1, Carlos Alberto Aguiar da Silva, Eduardo Barbosa Coelho

  • 1Department of Internal Medicine, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil.

American Journal of Hypertension
|October 10, 2006
PubMed

Insights

This study shows that while most antihypertensive drugs normalize blood pressure in hypertensive rats, losartan alone did not reduce arterial pressure variability, indicating potential autonomic imbalance. Further research into cardiovascular sympathetic modulation is suggested.

Area of Science:

  • Pharmacology
  • Cardiovascular Physiology
  • Autonomic Nervous System Research

Background:

  • Hypertension is a major risk factor for cardiovascular diseases.
  • Antihypertensive medications are crucial for managing elevated arterial pressure (AP).
  • The impact of different antihypertensive classes on AP variability and autonomic function in hypertension models requires further elucidation.

Purpose of the Study:

  • To investigate the effects of chronic administration of various antihypertensive agents on arterial pressure (AP) and heart rate variability.
  • To compare the efficacy of different pharmacologic classes in managing AP and its variability in a two-kidney, one-clip (2K1C) hypertensive rat model.
  • To assess the potential impact on autonomic modulation of the cardiovascular system.

Main Methods:

  • Chronic (15 days) oral administration of water, ramipril, losartan, atenolol, amlodipine, or hydrochlorothiazide to 2K1C hypertensive rats.
  • Continuous AP sampling via indwelling catheter in awake rats, with subsequent spectral analysis of systolic AP and pulse interval (PI).
  • Quantification of oscillatory components in low (LF) and high (HF) frequency bands to assess autonomic modulation.

Main Results:

  • All tested antihypertensive agents effectively reduced AP in 2K1C rats to normotensive levels.
  • Ramipril, atenolol, amlodipine, and hydrochlorothiazide normalized AP variability, unlike water-treated controls.
  • Losartan normalized AP but failed to reduce AP variability, showing increased LF components in systolic AP and PI, suggesting persistent sympathetic influence.

Conclusions:

  • While effective in lowering AP, different antihypertensive agents exhibit varied effects on cardiovascular autonomic regulation.
  • Losartan's inability to normalize AP variability in 2K1C rats suggests an underlying autonomic imbalance with heightened sympathetic modulation.
  • These findings highlight the importance of considering AP variability and autonomic function when selecting antihypertensive therapies.

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