Protein constituent contributes to the hypotensive and vasorelaxant acttvtties of cordyceps sinensis

Abstract

Cordyceps sinensis is a herb medicine in China for the treatment of general debility after sickness and for persons of advanced age. In the present study, cordyceps sinensis was extract by phosphate buffer saline (PBS) and dialyzed overnight against PBS using a membrane cut off at 3,500 dalton molecular weight. The resulting macromolecule fraction (defined as CS) was assayed in anesthetized rats for hypotensive effects and in isolated aorta for vasorelaxant effects. Intravenous injection of CS (8,16, 24 and 32 mg kg , respectively) suppressed significantly the mean arterial pressure (MAP) in a dose-dependent manner. 32 mg kg of CS induces the maximal hypotensive response with a 58 ± 4 mm Hg (from 107 ± 6 to 49 ± 3 mm Hg) change in MAP and a over 45 min action duration. In aortic rings precontracted with phenylephrine treatment with CS between 0.5 and 500 μg ml induced dose dependent relaxation. Maximal vasorelaxant response evoked by 150 μg ml CS was 68.9 ± 7.3 %. Furthermore, CS-induced vasorelaxation is mediated by the endothelium possibly by stimulating the release of the nitric oxide and endotheliumderived hyperpolarizing factor. In conclusion, the present study revealed that presence of a constituent in CS which reduces MAP by relaxing the vascular beds directly. However, the effect may be caused by a single active ingredient or by the combined action of many active agents found in the extract.