Abstract
Endothelin-1 (ET-1) is a potent vasoconstrictor involved in the regulation of vascular tone and implicated in hypertension. However, the role of small blood vessels endothelial ET-1 in hypertension remains unclear. The present study investigated the effect of chronic over-expression of endothelial ET-1 on arterial blood pressure and vascular reactivity using transgenic mice approach. Transgenic mice (TET-1) with endothelial ET-1 over-expression showed increased in ET-1 level in the endothelial cells of small pulmonary blood vessels. Although TET-1 mice appeared normal, they developed mild hypertension which was normalized by the ETA receptor (BQ123) but not by ETB receptor (BQ788) antagonist. Tail-cuff measurements showed a significant elevation of systolic and mean blood pressure in conscious TET-1 mice. The mice also exhibited left ventricular hypertrophy and left axis deviation in electrocardiogram, suggesting an increased peripheral resistance. The ionic concentrations in the urine and serum were normal in 8-week old TET-1 mice, indicating that the systemic hypertension was independent of renal function, although, higher serum urea levels suggested the occurrence of kidney dysfunction. The vascular reactivity of the aorta and the mesenteric artery was altered in the TET-1 mice indicating that chronic endothelial ET-1 up-regulation leads to vascular tone imbalance in both conduit and resistance arteries. These findings provide evidence for the role of spatial expression of ET-1 in the endothelium contributing to mild hypertension was mediated by ETA receptors. The results also suggest that chronic endothelial ET-1 over-expression affects both cardiac and vascular functions, which, at least in part, causes blood pressure elevation.
Highlights
Endothelin-1 (ET-1) is an endothelium-derived peptide with vasoconstriction and mitogenic properties [1]
ET-1 contributes to hypertension in deoxycorticosterone acetate (DOCA)-salt hypertensive rats and DOCA-salt treated spontaneous hypertensive rats (SHRs) [6,7,8], and ET receptor antagonists (LU135252, A127722.5 and bosentan) had been shown to lower blood pressure in various experimental hypertensive models [9,10,11,12]
We developed transgenic mice using the tyrosine kinase-1 promoter [20] to drive the expression of mouse ET-1 cDNA in vascular endothelial cells
Summary
Endothelin-1 (ET-1) is an endothelium-derived peptide with vasoconstriction and mitogenic properties [1] It exerts its vasoconstrictor effect by binding to G-protein coupled receptors (ETA or ETB) [2,3]. The arterial blood pressure elevation caused by ET-1 is accompanied by structural and functional changes in small arteries including vascular hypertrophy in different models of hypertension [8,13]. These pharmacological analyses suggest that ET-1 plays an important role in the pathogenesis of hypertension. This will avoid the concern of potential side effects of the drugs
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