function, reducing platelet adhesion, influencing ion channels, altering autonomic neurotransmitters release, improving lipid profiles', and glycaemic control (Zhou et al 2004).
Antihypertensive Red ginseng has been used as an antihypertensive agent in Korea, but its clinical effect is unclear despite several in vivo and in vitro experimental studies. Recent preliminary data suggests that the antihypertensive effects may be partly attributed to an angiotensin-converting enzyme (ACE) inhibitory effect demonstrated by P. ginseng extract in vitro (Persson et al 2006). These effects were additive to the traditional ACE inhibitor enalapril.
A study of isolated muscle preparations of animal heart and aorta with an alcohol-based extract of ginseng suggest that the hypotensive effect of ginseng is associated with a direct inhibition of myocardial contractility due to a reduction of calcium ion influx into cardiac cells, as well as the inhibition of catecholamine-induced contractility of vascular smooth muscles (Hah et al 1978).
In a prospective, randomised, double-blind placebo-controlled study of 30 healthy adults, 200 mg ginseng extract given for 28 days was found to increase the QTc interval and decrease diastolic blood pressure 2 hours after ingestion on the first day of therapy. These changes, however, were not thought to be clinically significant (Caron et al 2002).
Antiplatelet Although reports from recent in vitro and in vivo assays claim that P. ginseng is not one of the herbs that contributes to the antiplatelet effects of a Korean combination formula known as Dae-Jo-Hwan (Chang et al 2005), a number of studies have found that several ginsenosides inhibit platelet aggregation. Panaxynol has been shown to inhibit platelet aggregation induced by adenosine diphosphate (ADP), collagen and arachidonic acid. Panaxydol and ginsenosides Ro, Rg, and Rg2 inhibit rabbit platelets while panaxydol prevented platelet aggregation and thromboxane formation (Kuo et al 1990).
Antihyperlipidaemic Ginsenoside Rb1 has been shown to lower triglyceride and cholesterol levels via cAMP-production in the rat liver (Park et al 2002b). P. ginseng extract (6 g/day) for 8 weeks resulted in a reduction in serum total cholesterol, triglyceride, LDL and plasma malondialdehyde levels and an increase in HDL (Kim & Park 2003) in eight males. Ginseng has also been reported to decrease hepatic cholesterol and triglyceride levels in rats, indicating a potential use of ginseng in the treatment of fatty liver (Yamamoto et al 1983).
Other cardiovascular effects Ginsenoside Rb2 has been shown to enhance the fibrinolytic activity of bovine aortic endothelial cells (Liu et al 2003). In animal studies ginseng inhibits cardiomyocyte apoptosis induced by ischaemia and reperfusion
(Zeng et al 2004) and the crude saponins have been shown to reduce body weight, food intake, and fat content in rats fed a high-fat diet (Kim et al 2005a).
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