Protective effects of scutellarin on vascular dysfunction caused by hypertension in SHR rats

OBJECTIVE To investigate the effect of scutellarin(SCU),which is the main effective component of Erigeron breviscapus(Vant.)Hand-Mazz native to Yunnan in China,on vascular dysfunction(VD)of cardiac coronary artery(CA)and cerebral basilar artery(BA)caused by hypertension in SHR rats.METHODS 1.BA and CA vesselsrings from 40 weeks of SHR rats were isolated and equilibrated in organ bath with MOPS-PSS buffer and ring tension was recorded,comparing with a normal control of WKY rats.SCU was treated accumulatively after pre-contracted with vasoconstrictor U46619(1μmol·L-1).2.ACH and SNP were treated accumulatively after pre-incubation with SCU(300μmol·L-1,100μmol·L-1)and pre-contracted by U46619(1μmol·L-1),K+60mmol·L-1,respectively.While U46619 was added accumulatively to BA/CA rings pre-incubated with SCU(300and 100μmol·L-1).ACH-induced relaxation rate was to evaluate endothelium-dependent relaxation,and SNP-induced relaxation rate to evaluate the artery non-endothelium-dependent relaxation.RESULTS SCU significantly dilated both BA and CA rings pre-contracted by U46619 in old rats.EC50 value of SCU in WKY ratswas less than that in SHR(P<0.05),which showing VD of CA and BA in SHR rats.Compared with WKY group,ACH relaxation curve of SHR group shifted to the right,suggesting that hypertension induced VD.When SCU 300μmol·L-1 pre-treated CA groups and SCU 100μmol·L-1 pre-treated BA groups,EC50 to ACH was significantly lower(P<0.05).Likewise,the vasodilatation of CA/BA rings to SNP was also improved obviously when pre-treated with SCU,and Emax to SNP was decreased significantly(P<0.05).Moreover,EC50 to U46619was significantly lower when pre-treated by SCU.CONCLUSION In SHR rats,SCU antagonized U46619 on CA/BA rings in a noncompetitive manner.Furthermore,SCU should appear to protect VD induced by hypertension.