Effects of high sodium intake on cardiovascular aldosterone synthesis in stroke-prone spontaneously hypertensive rats.
OBJECTIVE
Aldosterone is synthesized in extra-adrenal tissues such as the vasculature, heart and brain. The mechanisms underlying the effect of high salt intake on the development and acceleration of vascular injury and cardiac hypertrophy in the stroke-prone spontaneously hypertensive rats (SHRSP) are still not clear. The goal of this study was to determine whether high salt intake increases cardiovascular aldosterone synthesis in SHRSP.


METHODS
Four-week-old SHRSP were given tap water or 0.9% NaCl solution for hydration for 4 weeks in addition to a normal salt diet. Isolated rat mesenteric arteries and hearts were perfused for 2 h, and the perfusate was analysed by high-performance liquid chromatography. The concentrations of aldosterone synthase gene (CYP11B2) mRNA and angiotensin II receptor (AT1R) mRNA were determined by competitive polymerase chain reaction.


RESULTS
Salt-loaded SHRSP had higher blood pressures than SHRSP with normal salt intake. Plasma aldosterone concentrations and plasma renin activity were decreased by high salt intake. Aldosterone production, the expression of CYP11B2 mRNA and AT1R mRNA in mesenteric arteries and hearts were significantly increased by high salt intake.


CONCLUSIONS
These results suggest that high salt intake increases aldosterone production and expression of the AT1R mRNA in the cardiovascular tissue in SHRSP, which may contribute to the development of malignant hypertension in salt-loaded SHRSP.
Takeda
Y
Y
Second Department of Internal Medicine, School of Medicine, Kanazawa University, Japan. takeday@im2.m.kanazawa-u.ac.jp
Yoneda
T
T
Demura
M
M
Furukawa
K
K
Miyamori
I
I
Mabuchi
H
H
D000450:Aldosterone / Q000096:biosynthesis*; D000818:Animals; D002319:Cardiovascular System / Q000378:metabolism*; D004032:Diet; D020022:Genetic Predisposition to Disease; D006973:Hypertension / Q000235:genetics* / Q000378:metabolism*; D066298:In Vitro Techniques; D008638:Mesenteric Arteries / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011918:Rats, Inbred SHR / Q000235:genetics; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin / Q000235:genetics; D012964:Sodium / Q000008:administration & dosage* / Q000494:pharmacology; D020521:Stroke / Q000235:genetics*
D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin; D000450:Aldosterone; D012964:Sodium