Short-term exposure to dexamethasone promotes autonomic imbalance to the heart before hypertension

Abstract

Hypertension is one of the chronic side effects of dexamethasone (DEX) treatment; however, almost nothing is known about its acute effects. Therefore, the aim of this study was to investigate the possible mechanisms involved in blood pressure control after acute or short-term DEX treatment in adult animals. Eighty Wistar rats were divided into four groups: C1 and C5, for rats treated with saline for 1 or 5 days, respectively; D1 and D5, for rats treated with DEX for 1 or 5 days, respectively (decadron, 1 mg/kg, i.p.). Heart rate was increased in DEX treatment, but arterial pressure and cardiac muscle mass were not altered. Only few and isolated changes on gene expression and protein level of renin-angiotensin system components were observed. Five days of DEX treatment, but not one day, determined an increase in sympathetic component of spectral analysis (+75.93%, P < .05) and a significant reduction of parasympathetic component (-18.02%, P < .05), which contributed to the autonomic imbalance to the heart (LF/HF, +863.69%). The results of this present study demonstrated, for the first time, that short-term exposure to DEX treatment impairs the autonomic balance to the heart before hypertension, which was independent of renin-angiotensin system.

Differential effects of dexamethasone on arterial stiffness, myocardial remodeling and blood pressure between normotensive and spontaneously hypertensive rats

“…and xylasine hydrochloride (10 mg/kg, i.p .) and the carotid artery was catheterized as published (Duchatsch et al, 2018). After 24 h recovery, BP was recorded in conscious rats using a Software LabChart Pro 7.1 (ADInstruments, NSW, Australia), as published (Duchatsch et al, 2018).…”

“…From the BP recordings, the variability of HR (heart rate) and SBP (systolic blood pressure), within frequency domain, was managed using the specific software (CardioSeries V2.7), as published (Duchatsch et al, 2018). Low‐frequency band power (LF) and high‐frequency band power (HF) were determined and the sympathovagal balance was analyzed by the LF/HF ratio (Duchatsch et al, 2018).…”

“…Dexamethasone (DEX)‐induced hypertension has been shown by our group and others in both animals (Constantino et al, 2017; Dodic et al, 1999; Herrera et al, 2017; Herrera, Duchatsch, Tardelli, Dionisio, Santos, et al, 2020; Jesus et al, 2020; Joukar et al, 2017; Mondo et al, 2006; Ong et al, 2013) and humans (Anwar et al, 2016; Brotman et al, 2005; Williamson et al, 2015), but the effects of DEX on arterial stiffness are still unclear. This secondary type of hypertension has been associated with increased sympathetic nerve activity and impaired baroreflex activity (Constantino et al, 2017; Duchatsch et al, 2018; Fletcher et al, 2003; Herrera et al, 2016; Segar et al, 2006), oxidative stress (Joukar et al, 2017; Mondo et al, 2006; Schafer et al, 2005), increased renin angiotensin system activity (Forhead et al, 2000; Forhead et al, 2015; Hoshino et al, 1994; Suzuki et al, 1982) and skeletal muscle rarefaction (Herrera et al, 2016; Herrera et al, 2017; Herrera, Duchatsch, Tardelli, Dionisio, Shinohara, et al, 2020; Jesus et al, 2020). Preliminary results from our laboratory (data not published) have suggested that DEX‐induced hypertension was associated arterial stiffness, but the mechanisms are not totally clear.…”

Dexamethasone and Training-Induced Cardiac Remodeling Improve Cardiac Function and Arterial Pressure in Spontaneously Hypertensive Rats

“…Then, a catheter was inserted into the carotid artery for arterial pressure measurement, as published. 7,21 After 24 h recovery, arterial pressure was recorded in awake rats, using a pressure transducer (DPT100; Utah Medical Products Inc., Midvale, Utah, USA) and an amplifier (Quad Bridge Amp, ADInstruments, NSW, Australia), connected to an acquisition board (Powerlab 4/35, ADInstruments, NSW, Australia).…”

“…Cardiac interval pulse from 15-30 min recordings (2,000 Hz) was processed by LabChart pro v7.1 software (ADInstruments, NSW, Australia) that applies an algorithm to detect cycle-tocycle inflection points in the pulsatile arterial pressure signal, as previously published. 21 Heart rate (HR) and systolic arterial pressure (SAP) variability analyses, within frequency domain, were managed using DIAS software (CardioSeries V2.7, http:// www.danielpenteado.com). Low frequency band power and high frequency band power were determined, corresponding to sympathetic and parasympathetic (LF) and parasympathetic (HF) nervous activity, respectively.…”