Prevention of hypertension, cardiovascular damage and endothelial dysfunction with green tea extracts.
BACKGROUND
We investigated the effect of green tea extract (GTE) in arterial hypertension with high oxidative stress. Angiotensin (Ang) II induces endothelial dysfunction (ED) that is crucial for the development of atherosclerosis and hypertension.


METHODS
Male Sprague-Dawley rats, 13 weeks old, randomly assigned to drinking water with or without GTE (6 mg/mL) received a vehicle, a high (700 microg/kg/d) or a low (350 microg/kg/d) Ang II dose for 13 days, by osmotic mini-pumps. Blood pressure (BP) was measured with telemetry. After sacrifice, left ventricular (LV) mass index, small mesenteric artery media-to-lumen ratio, and concentration-response curves of phenylephrine-precontracted arteries to acetylcholine were evaluated. The effect of the superoxide dismutase (SOD-1) analog tempol on artery responses to acetylcholine was assessed. Oxidative stress was measured by plasma hydroperoxides and nitrotyrosine levels. The mRNA of heme oxygenase 1 (HO-1), NADPH oxidase endothelial p22(phox) subunit, and SOD-1 was also measured in the aorta.


RESULTS
Compared with vehicle high Ang II increased BP, LV mass index, media-to-lumen ratio, and hydroperoxide radicals. The GTE blunted these increases, prevented the increase in HO-1, p22(phox), and SOD-1 mRNA in aorta caused by Ang II, and reduced them below baseline levels. Low Ang II dose increased BP values and plasma hydroperoxides only during the first week. Both Ang II doses shifted rightward the curves to acetylcholine; this was prevented in vivo by GTE and abolished in vitro by tempol.


CONCLUSIONS
The GTE prevented hypertension and target organ damage induced by a high Ang II dose, likely by prevention or scavenging of superoxide anion generation.
Department of Vascular Surgery, University of Padova, Padova, Italy.
Michele
M
Antonello
Domenico
D
Montemurro
Massimo
M
Bolognesi
Marco
M
Di Pascoli
Anna
A
Piva
Franco
F
Grego
Daniele
D
Sticchi
Luisa
L
Giuliani
Spiridione
S
Garbisa
Gian Paolo
GP
Rossi
D000804:Angiotensin II / Q000037:antagonists & inhibitors / Q000633:toxicity; D000818:Animals; D001011:Aorta / Q000201:enzymology / Q000473:pathology; D001794:Blood Pressure; D028241:Camellia sinensis; D002318:Cardiovascular Diseases / Q000139:chemically induced / Q000209:etiology / Q000517:prevention & control*; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000473:pathology; D006339:Heart Rate; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism; D006973:Hypertension / Q000150:complications / Q000517:prevention & control*; D008297:Male; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D008517:Phytotherapy; D010936:Plant Extracts / Q000627:therapeutic use; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D000072105:Superoxide Dismutase-1; D013481:Superoxides / Q000378:metabolism
D010936:Plant Extracts; D012333:RNA, Messenger; D013481:Superoxides; D000804:Angiotensin II; D051547:Heme Oxygenase-1; C000606292:Sod1 protein, rat; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D019255:NADPH Oxidases; C515768:Cyba protein, rat