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.

Hyperhomocysteinemia predicts total and cardiovascular mortality in high-risk women.

OBJECTIVE: The impact of homocysteine on cardiovascular disease can be more detrimental in women than in men, but it is unknown whether this applies to high-risk women. We therefore investigated the association of hyperhomocysteinemia with coronary artery disease (CAD) and cardiovascular mortality in high-risk women referred for CAD, both in the total population and in the hypertensive and normotensive cohorts. DESIGN: A prospective study cohort. SETTING: A tertiary centre. INCLUSION CRITERIA: 262 consecutive Caucasian postmenopausal women referred for coronary angiography. EXCLUSION CRITERIA: acute myocardial infarction and vitamin supplementation. MAIN OUTCOME MEASURE(S): We assessed total plasma homocysteine (tHcy), folate levels, and the MTHFR677C-->T polymorphism. CAD was defined as a modified Duke Index score greater than 0; hyperhomocysteinemia as tHcy levels of 15 micromol/l or greater. The primary study outcome was cardiovascular mortality at follow-up. RESULTS: Mild/moderate and severe hyperhomocysteinemia was found in 15.1 and 1.6% of women, respectively, without differences between CAD and non-CAD women. By the ATPIII criteria, 92.2% of the women were in the highest risk class and 55% had CAD; however, no association of tHcy with the CAD score was found. After a median follow-up of 3.6 years, 23 women (9.1%) had died, 15 (6%) of cardiovascular causes. Women with high tHcy levels showed the worst all-cause and cardiovascular death-free survival at Kaplan-Meier and Cox regression analysis. Moreover, in the hypertensive cohort only women with hyperhomocysteinemia showed increased cardiovascular mortality. CONCLUSION: Hyperhomocysteinemia is common in high-risk women and adversely affects their prognosis, although it is unrelated to the CAD atherosclerotic burden.

Is homocysteine important as risk factor for coronary heart disease?

AIM: Homocysteine (Hcy), a sulfur-containing amino acid product of methionine metabolism, may play an important role in the development of cardiovascular disease. In this paper we review available knowledge on the pathways leading to synthesis and degradation of Hcy, as well as on the genetic and environmental factors affecting its plasma levels, focussing on its potential role in the development of coronary heart disease. DATA SYNTHESIS: Hyperhomocysteinemia (HHcy) is determined by genetic and environmental factors and represents a modifiable cardiovascular risk factor since vitamin supplementation has been shown to effectively lower plasma homocysteine levels. While case-control and cross-sectional studies consistently showed an association of HHcy with cardiovascular disease, prospective studies have given conflicting results. Thus, the role of HHcy in the development of coronary heart disease is still under debate. Furthermore, it remains unclear which patients should be screened for HHcy and treated to correct HHcy. CONCLUSIONS: Available information collectively suggests that although HHcy can be regarded as a minor risk factor for coronary heart disease, it interacts with other risk factors in triggering new events in patients with known CAD. Thus, the treatment of mild HHcy with folate supplementation is appropriate in particular in high risk patients or patients with established CAD who do not present with the "traditional" risk factors.