Effects of Shenfu Injection and Its Main Components on the Contraction of Isolated Rat Thoracic Aortic Rings

BACKGROUND AND PURPOSE Shenfu injection (SFI), derived from the ancient traditional Chinese medicine (Red Radix Ginseng and Radix Aconitum Carmichaeli), has been widely used in the clinical for the treatment of cardiovascular diseases for more than 20 years. The present study aims to investigate the effects of SFI and its main components on the contraction of isolated rat thoracic aorta rings and the potential mechanisms of this action. METHODOLOGY/PRINCIPAL FINDINGS The isolated rat thoracic aorta rings were initially treated with different concentrations of SFI, Hongshen injection (HSI, mainly containing ginsenoside) or Fupian injection (FPI, mainly containing aconite total alkaloids) separately. The control group was added an equal volume Krebs-Henseleit (K-H) solution. All three injections exhibited no obviously effects on the basal tension of the rings in the resting state. However, in the isolated thoracic aorta rings with intact endothelium, when the rings were first induced by 60 mM potassium chloride (KCl) or 1 µM norepinephrine (NE) to the maximal contraction and then treated with above injections, SFI and HSI significantly inhibited the vasoconstriction induced by KCl or NE. In addition, FPI has a tendency to inhibit KCl-induced vasoconstriction and facilitate NE-induced vasoconstriction, but no significant difference. None of them showed obvious effect on the endothelium denuded vessels. Moreover, this procedure was repeated after pre-incubation of nitric oxide synthase (NOS) inhibitor N(G)-nitro- L-arginine methyl ester (L-NAME), which suppressed the vasorelaxation effect of SFI and HSI. CONCLUSIONS AND IMPLICATIONS These results demonstrate that both SFI and HSI caused an apparent thoracic aorta relaxation by endothelium-dependent manner, which was associated with eNOS system, while FPI had no detectable vasodilator effect. This suggested that the ginsenoside from red Radix Ginseng may be the main active ingredient of SFI's vasodilator effect.