Abstract

Hydroxysafflor yellow A, the main active component of safflor yellow, in this study is used to investigate the vascular activity of hydroxysafflor yellow A (HSYA) on rat thoracic aorta and the underlying mechanism. The tension of the isolated thoracic aorta rings of rats incubated with different concentrations of HSYA was measured using organ bath technique. The effect of HSYA (10^-4~10^-6 mol/L) on the contraction induced by cumulative phenylephrine, KCl and CaCl₂, was respectively examined by HSYA (10^-4~10^-6 mol/L) dose, which dependently inhibited the contraction induced by KCl (6×10^-2 mol/L) or phenylephrine (PE, 10^-6 mol/L) in both endothelium-intact and endothelium-denuded aortic rings. HSYA inhibited the CaCl₂-induced contraction and downward shifted concentration-response curve of aortic rings precontracted with PE. Furthermore, HSYA-induced inhibition may be partially through the blockage of IP3 receptor. These results indicated that the role of HSYA may be involved in the reduction of Ca²⁺ influx and inhibition of IP3 receptor in vascular smooth muscle cells.

Key words: Hydroxysafflor yellow A, vasodilation, Ca²⁺ channel, aorta.