Honokiol Shu Vascular Function And Related Mechanism Research

Thromboembolic is the main pathogenic factors of cardiovascular and cerebrovascular diseases. Vascular endothelial cells play an important role in the occurrence of thrombosis, It can be endogenous synthesis and releases activly substances including Prostacyclin、Nitric oxide、Tissue plasminogen et al.Honokiol is a main biphenyl neolignan isolated from traditional Chinese medicine Hou pu,cortex of Magnolia officinalis(Magnoliaceae), which has a variety of pharmacological effects such as anti-platelet aggregation, prevent cerebral injury caused by middle cerebral artery occlusion and cerebral ischemia reperfusion injury, significantly decreased the percentage of apoptotic endothelial cells induced by oxidized low-density lipoprotein (ox-LDL), up-regulate prostacyclin synthease’s expression. Whether these effects only come from PGI2 was not clear yet. The following study explores its action mechanism on the Contraction of Rat thoracic aorta and the NO synthesis In endothelial cells, further explaining honokiol’s Vasodilator effect. Indomethacin, an inhibitor of cyclooxygenase (COX) and tranylcypromine, and a prostacyclin synthease inhibitor were used to ascertain whether the NO in Rat aortic endothelial cells is affected by honokiol.Results:Honokiol can significantly and concentration-dependent (4.7-37.6μmol/L) inhibite the contraction which induced by KCl, phenylephrine, norepinephrine or Tran on rat thoracic aorta., and IC50-Tran<IC50-PHE<IC50-KCl. Honokiol can significantly and concentration-dependent (0.376-37.6μmol/L) increase the NO content in culture medium of endothelial cells. L-NAME can significantly reduce the NO content of culture medium but the Indo has a increasing effect. Honokiol can alter the effect of Tran which can increase the NO content of culture medium.Conclusion:This study found the role of Honokiol of vasodilation for the first time, which was associated with promoting the release of NO and the activation of PGIS in endothelial cells. Inhibition of ion channel and antagonisting a-receptor are also involved in this mechanism Honokiol can increase in NO synthesis alone while synthesizing PGI2 in endothelial cells. When the physiological environment is short of PGI2, NOS protein will be activated or expressed for synthesizing NO that can maintain the physiological activity.