Increased Dietary Salt Changes Baroreceptor Sensitivity and Intrarenal Renin-Angiotensin System in Goldblatt Hypertension
Data
2017
Autores
Shimoura, Caroline Gusson 
Lincevicius, Gisele Silvério
Nishi, Erika Emy
Simon, Karin Argenti
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BACKGROUND Renovascular hypertension (2-kidney 1-clip model (2K1C)) is characterized by renin-angiotensin system (RAS) activation. Increased Angiotensin II (AngII) leads to sympathoexcitation, oxidative stress, and alterations in sodium and water balance. AIM The aim of this study was to evaluate whether a discrete increase in sodium chloride intake in 2K1C rats leads to changes in cardiovascular and autonomic function, oxidative stress, and renin angiotensin aldosterone system. METHODS After 4 weeks of induction of hypertension, rats were fed a normal sodium diet (0.4% NaCl) or a high-sodium diet (2% NaCl) for 2 consecutive weeks. Experiments were carried out for 6 weeks after clipping. Mean arterial pressure (MAP), renal sympathetic nerve activity (rSNA), arterial baroreflex control of rSNA, and heart rate (HR) were assessed. Thiobarbituric acid reactive substances and glutathione were measured as indicators of systemic oxidative stress. Angiostensinconverting enzyme (ACE), ACE2, and angiotensinogen were evaluated in clipped and unclipped kidneys as also urinary angiotensinogen and plasma renin activity. Angiotensinogen, plasma renin activity (PRA) and angiotensin-converting enzyme (ACE) and ACE2 in clipped and unclipped kidneys were evaluated. RESULTS High-sodium diet did not change systemic oxidative stress, and basal values of MAP, HR, or rSNA
however, increased renal (-0.7 +/- 0.2 vs. -1.5 +/- 0.1 spikes/s/mm Hg) and cardiac (-0.9 +/- 0.14 vs. -1.5 +/- 0.14 bpm/mm Hg) baroreceptor reflex sensitivity in 2K1C rats. Although there was no alteration in PRA, a high-salt diet significantly decreased urinary angiotensinogen, ACE, and ACE2 expressions in the clipped and unclipped kidneys. CONCLUSIONS Increased arterial baroreceptor control associated with a suppression of the intrarenal RAS in the 2K1C rats on high-salt diet provide a saltresistant effect on hypertension and sympathoexcitation in renovascular hypertensive rats.
however, increased renal (-0.7 +/- 0.2 vs. -1.5 +/- 0.1 spikes/s/mm Hg) and cardiac (-0.9 +/- 0.14 vs. -1.5 +/- 0.14 bpm/mm Hg) baroreceptor reflex sensitivity in 2K1C rats. Although there was no alteration in PRA, a high-salt diet significantly decreased urinary angiotensinogen, ACE, and ACE2 expressions in the clipped and unclipped kidneys. CONCLUSIONS Increased arterial baroreceptor control associated with a suppression of the intrarenal RAS in the 2K1C rats on high-salt diet provide a saltresistant effect on hypertension and sympathoexcitation in renovascular hypertensive rats.
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American Journal Of Hypertension. Oxford, v. 30, n. 1, p. 28-36, 2017.