Aim To investigate the effects of the Lobelia Chinensis Lour Alkaloids(LCLA)on endothelin-1(ET-1)mRNA expression and endothelin synthesis and release in renal hypertensive rats(RHR).Methods The glodblatt renovascular hypertension model was induced in rats by two-kidney one clip method.After 4 weeks the rats were divided into 3 groups,including the hypertensive group,the captopril group and the LCLA group,while the control group was given sham-operation.Using in situ hybridization to observe ET-1 mRNA expression in peripheral blood leucocytes.Using immunohistochemical technique to count positive rate of ET in “en face” preparations of arterial endothelium to reflect the synthesis of ET.Using radioimmunoassay to examine the level of ET in serum.Results Compared with the sham operation group,the positive rate of ET-1 mRNA in peripheral blood leucocytes(34.64%±8.39% vs 9.34%±4.47%,p<0.05),the positive rate of ET in arterial endothelium(7.42%±0.24% vs 1.58%±0.24%,p<0.05)and the plasma concentration of ET(221±24 ng/L vs 138±19 ng/L,p<0.05)were increased significantly in hypertensive rats.After treating with LCLA for 8 w,compared with the hypertensive group,ET-1 mRNA expression(20.38%±11.31% vs 34.64%±8.39%,p<0.05),endothelin(ET)synthesis(3.53%±0.21% vs 7.42%±0.24%,p<0.05)and release(191±21 ng/L vs 221±24 ng/L,p<0.05)were significantly inhibited.Conclusions The expression of ET was increased in RHR.The LCLA can inhibit the expression of ET in the transcriptional and translational level which may be effective to the preventing and treatment of the renal hypertension.