White mulberry fruit polysaccharides enhance endothelial nitric oxide production to relax arteries in vitro and reduce blood pressure in vivo

https://doi.org/10.1016/j.biopha.2019.109022Get rights and content
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Abstract

Mulberry fruit polysaccharides have demonstrated excellent anti-inflammatory, antioxidant, hypolipidemic, and hypoglycemic properties. This study tested the effect of white mulberry fruit polysaccharides (WMFPs) on blood pressure. WMFPs induced endothelium-dependent relaxation in rat mesenteric arteries and NO production in endothelial cells, both of which were reversed by the NO synthase inhibitor Nω-nitro-l-arginine methyl ester hydrochloride, a phosphoinositide 3-kinase inhibitor LY294002, a cell-permeable Ca2+ chelator (1,2-bis (o-aminophenoxy) ethane-N,N,N’,N’-tetraacetic acid (acetoxymethyl ester)), and inhibitors of molecules downstream of NO, including the soluble guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, the potassium channel inhibitor tetraethylammonium chloride, the large conductance calcium-activated potassium channel-specific inhibitor iberiotoxin, and the KATP channel inhibitor glibenclamide. Intravenous injection of WMFPs reduced mean arterial blood pressure in both normotensive Sprague-Dawley and spontaneously hypertensive rats through enhanced endothelial NO production. This study demonstrated that WMFPs induce endothelium-dependent relaxation in rat mesenteric arteries to regulate blood pressure, suggesting that development of WMFPs as a novel antihypertensive agent is warranted.

Abbreviations

BAPTA-AM
1,2-bis o-aminophenoxy ethane-N,N,N′,N′-tetraacetic acid (acetoxymethyl ester)
BKCa
large conductance calcium-activated potassium channel
DAF-FM DA
4-amino-5-methylamino-2′,7′-difluorofluorescein
IbTX
iberiotoxin
L-NAME
Nω-nitro-l-arginine methyl ester hydrochloride
MAEC
mesenteric artery endothelial cell
MAP
mean arterial pressure
NO
nitric oxide
NPSS
normal physiological saline solution
ODQ
1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one
PGI2
prostacyclin
Phe
phenylephrine
SHR
spontaneously hypertensive rat
TEA
tetraethylammonium chloride
WMFPs
white mulberry fruit polysaccharides

Keywords

Hypertension
Nitric oxide
Soluble guanylyl cyclase
WMFPs
Vessel relaxation

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1

Both authors contributed equally to the work.