What is the clinical evidence from this study?

Study design: Other. Population: Hypertension (n=275). Intervention: Low-intensity aerobic training vs. Sedentary control. Primary outcome: Ang II/Ang (1-7) ratio in the renal artery (36% reduction, p=<0.05).

January 1, 2015Circulation Journal49 citationsOpen Access

Downregulation of the Vascular Renin-Angiotensin System by Aerobic Training　– Focus on the Balance Between Vasoconstrictor and Vasodilator Axes –

Q: What are the key findings of this study?

Aerobic training in spontaneously hypertensive rats significantly reduced the Ang II/Ang (1-7) ratio in the renal artery by 36% and lowered mean arterial pressure by 5%.

SSSebastião D. Silva TZThais T. Zampieri ARAdriana Ruggeri

Key Result

Aerobic training in spontaneously hypertensive rats significantly reduced the Ang II/Ang (1-7) ratio in the renal artery by 36% and lowered mean arterial pressure by 5%.

Structured PICO

Does aerobic training downregulate the vascular renin-angiotensin system in spontaneously hypertensive rats?

Population

275 male spontaneously hypertensive and normotensive Wistar-Kyoto rats, aged 11-12 weeks, were allocated to 12 weeks of aerobic training or sedentary control to evaluate vascular renin-angiotensin system changes.

Intervention

Low-intensity aerobic training on a treadmill (50-60% of maximal exercise capacity), performed 5 days/week for 12 weeks, up to 1 hour/day.

Comparator

Sedentary protocol (handled every day and submitted once a week to short periods of mild exercise: 5-10 min; 0.4-0.8 km/h; 0% grade).

Outcome

Sequential effects of training on vascular angiotensinogen expression, Ang II, and Ang (1-7) content in arteries, kidney, and plasma.surrogate

Aerobic training downregulates the vasoconstrictor axis of the renin-angiotensin system specifically in the renal artery of hypertensive rats, contributing to blood pressure reduction.

Main Result

Effect estimate: 36% reduction

p-value: p=<0.05

Limitations

Technical limitations (small amount of protein extracted and non-specific selectivity of commercially available AT1 receptor antibodies) precluded the quantification of sequential training effects on angiotensins' receptors in the renal artery.

Abstract

BACKGROUND: Hyperactivity of the renin-angiotensin system (RAS) and functional deficits in hypertension are reduced after exercise training. We evaluate in arteries, kidney and plasma of hypertensive rats the sequential effects of training on vascular angiotensinogen, Ang II and Ang (1-7) content. METHODS AND RESULTS: Spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) were trained or kept sedentary (S) for 3 months. After hemodynamic measurements (weeks 0, 1, 2, 4, 8 and 12), blood, arteries and kidneys were obtained to quantify the angiotensin content (HPLC) and angiotensinogen expression (Western Blotting). SHR-S vs. WKY-S exhibited elevated pressure, increased angiotensinogen and angiotensins' content in the renal artery with a high Ang II/Ang (1-7) ratio (~5-fold higher than in the femoral artery, kidney and plasma, and 14-fold higher than in the aorta). Training promptly reduced angiotensinogen expression and downregulated the RAS in the renal SHR artery (1st-12th week), with a specific reduction of the vasoconstrictor axis; significant reduction of the AngII/Ang (1-7) ratio (36%, T4-T8) occurred simultaneously with significant pressure fall (5%). In other SHR arteries, plasma and kidneys and in all WKY tissues, T-induced AngII and Ang (1-7) reductions were proportional, maintaining the AngII/Ang (1-7) ratio. CONCLUSIONS: Vascular RAS is not equally expressed in vessels, having crucial importance in the renal artery. In the renal SHR artery, training downregulates the vasoconstrictor and preserves the vasodilator axis while in other tissues and plasma training reduces both RAS axes, thus maintaining the vasoconstriction/vasodilatation balance in a lower level.

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