Reduction of eNOS in Vascular Smooth Muscle by Salt Independently of Hypertension.
Endothelial nitric oxide synthase (eNOS) is known to be expressed in endothelium and smooth muscle cells of arteries. The aim of this study was to investigate the expression of eNOS in intimal and medial layer of aorta from rats fed with a high salt diet and its modulation by losartan and tempol.



Rats were fed during three weeks with: normal salt diet (NS, 0.4% NaCl); high salt diet (HS, 8% NaCl); NS plus tempol 1 mM (NS-T); HS plus tempol (HS-T); NS plus losartan 40mg.kg-1 (NS-L) and HS plus losartan (HS-L). Systolic blood pressure was recorded by the tail cuff method. Rats were then anaesthetized and the thoracic aorta and small arteries (bronchial branches of aorta) were processed to evaluate the expression of eNOS and aquaporin-1 (AQP-1) by immunohistochemistry.



HS group showed increased systolic blood pressure, increased eNOS and AQP-1 immunoexpression in the aorta intimal layer, and decreased eNOS immunoexpression in the aorta medial layer, respect to NS group. Losartan and tempol prevented hypertension and changes in the expression of eNOS and AQP-1 of the intimal layer. However, only tempol increased the expression of eNOS elicited by sodium overload in the medial layer of the aorta and small arteries respect to HS group.



A high salt diet decreases eNOS expression in vascular smooth muscle layers of aorta and small arteries, which is reversed by tempol. These results suggest an adverse effect of oxidative stress on vascular eNOS in rats fed a high salt diet independently of hypertension.
Cardiological Research Institute, National Council of Scientific and Technical Research, Buenos Aires, Argentina
Natalia L. Rukavina
NLR
Mikusic
Cardiological Research Institute, National Council of Scientific and Technical Research, Buenos Aires, Argentina
María I.
MI
Rosón
Cardiological Research Institute, National Council of Scientific and Technical Research, Buenos Aires, Argentina
Silvana L. Della
SLD
Penna
Cardiological Research Institute, National Council of Scientific and Technical Research, Buenos Aires, Argentina|Department of Pathophysiology, School of Pharmacy and Biochemistry, University of Buenos Aires, Buenos Aires, Argentina
Marcelo R
MR
Choi
Department of Pharmacology, School of Pharmacy and Biochemistry, University of Buenos Aires, Buenos Aires, Argentina
Susana
S
Gorzalczany
Department of Pathophysiology, School of Pharmacy and Biochemistry, University of Buenos Aires, Buenos Aires, Argentina
Elsa
Zotta
Cardiological Research Institute, National Council of Scientific and Technical Research, Buenos Aires, Argentina
Jorge E
JE
Toblli
Cardiological Research Institute, National Council of Scientific and Technical Research, Buenos Aires, Argentina
Belisario E
BE
Fernández
AQP-1; endothelium; eNOS; high salt intake; losartan; tempol