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Dynamic resistance training decreases sympathetic tone in hypertensive ovariectomized rats.

Shimojo GL, Palma RK, Brito JO, Sanches IC, Irigoyen MC, De Angelis K - Braz. J. Med. Biol. Res. (2015)

Bottom Line: Sympathetic tone was also lower in the trained group.Moreover, sympathetic tone was positively correlated with resting HR (r=0.7, P<0.05).This benefit may be associated with resting bradycardia and reduced cardiac sympathetic tone after training, which suggests potential benefits of resistance exercise for the management of hypertension after ovarian hormone deprivation.

View Article: PubMed Central - PubMed

Affiliation: Laboratório de Fisiologia Translacional, Programa de Ciências da Reabilitação, Universidade Nove de Julho, São Paulo, SP, Brasil.

ABSTRACT
The aim of this study was to investigate the effects of resistance exercise training on hemodynamics and cardiac autonomic control in ovariectomized spontaneously hypertensive rats. Female rats were divided into 4 groups: sedentary control (SC), sedentary hypertensive (SH), sedentary hypertensive ovariectomized (SHO), and resistance-trained hypertensive ovariectomized (RTHO). Resistance exercise training was performed on a vertical ladder (5 days/week, 8 weeks) at 40-60% maximal load. Direct arterial pressure was recorded. Vagal and sympathetic tones were measured by heart rate (HR) responses to methylatropine (3 mg/kg, iv) and propranolol (4 mg/kg, iv). Ovariectomy resulted in additional increases in blood pressure in hypertensive rats and was associated with decreased vagal tone. Resistance exercise trained rats had lower mean arterial pressure than untrained rats (RTHO: 159±2.2 vs SHO: 177±3.4 mmHg), as well as resting bradycardia (RTHO: 332±9.0 vs SHO: 356±5 bpm). Sympathetic tone was also lower in the trained group. Moreover, sympathetic tone was positively correlated with resting HR (r=0.7, P<0.05). The additional arterial pressure increase in hypertensive rats caused by ovarian hormone deprivation was attenuated by moderate-intensity dynamic resistance training. This benefit may be associated with resting bradycardia and reduced cardiac sympathetic tone after training, which suggests potential benefits of resistance exercise for the management of hypertension after ovarian hormone deprivation.

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Correlations between A, resting heart rate and sympathetic tone (r=0.7,P<0.05) and B, resting heart rate and vagal tone (r=0.2, P>0.05). Pearson'scorrelation coefficients were determined using data from all hypertensivegroups.
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f02: Correlations between A, resting heart rate and sympathetic tone (r=0.7,P<0.05) and B, resting heart rate and vagal tone (r=0.2, P>0.05). Pearson'scorrelation coefficients were determined using data from all hypertensivegroups.

Mentions: Correlation analysis involving all hypertensive rats (SH, SHO and RTHO groups) showed asignificant positive correlation between sympathetic tone and heart rate (r=0.7,P<0.05; Figure 2A). There was no correlationbetween vagal tone and heart rate (r=0.2, P>0.05; Figure 2B).


Dynamic resistance training decreases sympathetic tone in hypertensive ovariectomized rats.

Shimojo GL, Palma RK, Brito JO, Sanches IC, Irigoyen MC, De Angelis K - Braz. J. Med. Biol. Res. (2015)

Correlations between A, resting heart rate and sympathetic tone (r=0.7,P<0.05) and B, resting heart rate and vagal tone (r=0.2, P>0.05). Pearson'scorrelation coefficients were determined using data from all hypertensivegroups.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4470311&req=5

f02: Correlations between A, resting heart rate and sympathetic tone (r=0.7,P<0.05) and B, resting heart rate and vagal tone (r=0.2, P>0.05). Pearson'scorrelation coefficients were determined using data from all hypertensivegroups.
Mentions: Correlation analysis involving all hypertensive rats (SH, SHO and RTHO groups) showed asignificant positive correlation between sympathetic tone and heart rate (r=0.7,P<0.05; Figure 2A). There was no correlationbetween vagal tone and heart rate (r=0.2, P>0.05; Figure 2B).

Bottom Line: Sympathetic tone was also lower in the trained group.Moreover, sympathetic tone was positively correlated with resting HR (r=0.7, P<0.05).This benefit may be associated with resting bradycardia and reduced cardiac sympathetic tone after training, which suggests potential benefits of resistance exercise for the management of hypertension after ovarian hormone deprivation.

View Article: PubMed Central - PubMed

Affiliation: Laboratório de Fisiologia Translacional, Programa de Ciências da Reabilitação, Universidade Nove de Julho, São Paulo, SP, Brasil.

ABSTRACT
The aim of this study was to investigate the effects of resistance exercise training on hemodynamics and cardiac autonomic control in ovariectomized spontaneously hypertensive rats. Female rats were divided into 4 groups: sedentary control (SC), sedentary hypertensive (SH), sedentary hypertensive ovariectomized (SHO), and resistance-trained hypertensive ovariectomized (RTHO). Resistance exercise training was performed on a vertical ladder (5 days/week, 8 weeks) at 40-60% maximal load. Direct arterial pressure was recorded. Vagal and sympathetic tones were measured by heart rate (HR) responses to methylatropine (3 mg/kg, iv) and propranolol (4 mg/kg, iv). Ovariectomy resulted in additional increases in blood pressure in hypertensive rats and was associated with decreased vagal tone. Resistance exercise trained rats had lower mean arterial pressure than untrained rats (RTHO: 159±2.2 vs SHO: 177±3.4 mmHg), as well as resting bradycardia (RTHO: 332±9.0 vs SHO: 356±5 bpm). Sympathetic tone was also lower in the trained group. Moreover, sympathetic tone was positively correlated with resting HR (r=0.7, P<0.05). The additional arterial pressure increase in hypertensive rats caused by ovarian hormone deprivation was attenuated by moderate-intensity dynamic resistance training. This benefit may be associated with resting bradycardia and reduced cardiac sympathetic tone after training, which suggests potential benefits of resistance exercise for the management of hypertension after ovarian hormone deprivation.

Show MeSH
Related in: MedlinePlus