Jiajing et al.: Effects of Cyathula officinalis Kuan Extracts on Hypertension-induced Renal Vascular Remodelling The aim of this study was to investigate the role of the extracts of Cyathula officinalis Kuan on blood pressure in spontaneously hypertensive rats and the possible mechanisms involved. Blood pressure was recorded, renal vascular remodelling was visualized through haematoxylin and eosin staining and the expression of aldosterone, renin and angiotensin II in serum and kidney of spontaneously hypertensive rats was measured by real-time polymer chain reaction and enzyme-linked immuno-sorbent assay, respectively. The extracts of Cyathula officinalis Kuan significantly decreased the high blood pressure and reduced renal artery narrowing in spontaneously hypertensive rats. Moreover, Cyathula officinalis Kuan extracts also decreased the expression of aldosterone, renin and angiotensin II in both the serum and the kidney and activated ERK1/2 and p38 signalling pathways in kidney of spontaneously hypertensive rats. However, the toxicity to rat liver and kidney did not differ significantly between the extracts of Cyathula officinalis Kuan and enalapril, a well-known prodrug providing antihypertensive actions. These results demonstrated that the extracts from Cyathula officinalis Kuan can ameliorate hypertension-induced renal vascular remodelling in a rat models through inhibiting the expression of aldosterone, renin and angiotensin II and activating ERK1/2 and p38 signalling pathways.